If you call this with argument "unused=true" it searches for the translation strings that exist in en_US but are never used.
IMPORTANT: that can take quite a lot of time (up to 10 minutes), you need to tune the max_execution_time on your php.ini accordingly.

Duplicate strings in lang files in /home/jedica/www/dolibarr/dev/translation/../../htdocs/langs/en_US/ - 96 found

#StringFile and lines
1ShowAccountingJournalaccountancy.lang (91 - Show accounting journal) (292 - Show accounting journal)
27FeatureNotAvailableWithReceptionModuleadmin.lang (2012 - Feature not available when module Reception is enabled) (2017 - Feature not available when module Reception is enabled)
32NewAssetTypeassets.lang (24 - New asset type) (64 - New asset type)
54NotTheAssignedApproverholiday.lang (77 - You are not the assigned approver) (101 - You are not the assigned approver)
57Language_es_GTlanguages.lang (36 - Spanish (Guatemala)) (44 - Spanish (USA))
89unitGproducts.lang (198 - Gram) (206 - Gram)
90unitMproducts.lang (199 - Meter) (210 - Meter)
91unitM2products.lang (201 - Square meter) (216 - Square meter)
92unitM3products.lang (202 - Cubic meter) (222 - Cubic meter)
93Receptionreceptions.lang (4 - Reception) (7 - Reception)
94Receptionsreceptions.lang (5 - Receptions) (8 - Receptions)
96ImportSitewebsite.lang (77 - Import website template) (121 - Import website)
3ByYearaccountancy.lang (203 - By year)
main.lang (791 - By year)
29Eventsagenda.lang (12 - Events)
main.lang (899 - Events)
40ShowDetailsblockedlog.lang (16 - Show stored details)
main.lang (1059 - Show details)
44Browsercashdesk.lang (91 - Browser)
main.lang (710 - Browser)
49StatusToPaycompta.lang (66 - To pay)
main.lang (422 - To pay)
56StatusInterInvoicedinterventions.lang (30 - Billed)
main.lang (507 - Invoiced)
58Closedmain.lang (144 - Closed)
ticket.lang (70 - Closed)
59ConfirmCloneAskmain.lang (177 - Are you sure you want to clone the object <b>%s</b>?)
supplier_proposal.lang (37 - Are you sure you want to clone the price request <b>%s</b>?)
60Typemain.lang (221 - Type)
ticket.lang (74 - Type)
61MulticurrencyPaymentAmountmain.lang (366 - Payment amount, original currency)
multicurrency.lang (19 - Payment amount, original currency)
62Categorymain.lang (483 - Tag/category)
ticket.lang (75 - Analytic code)
63OpenAllmain.lang (510 - Open (All))
stocks.lang (154 - Open for all actions)
64Rejectsmain.lang (525 - Rejects)
withdrawals.lang (40 - Rejects)
65NotReadmain.lang (661 - Not read)
ticket.lang (63 - Not read)
6InternalUseradmin.lang (49 - Internal user)
users.lang (68 - Internal user)
7NewModuleadmin.lang (210 - New module)
modulebuilder.lang (8 - New module)
8NoticePeriodadmin.lang (270 - Notice period)
holiday.lang (113 - Notice period)
9LanguageFileadmin.lang (369 - Language file)
modulebuilder.lang (50 - File for language)
10PriceFormatInCurrentLanguageadmin.lang (410 - Price Format In Current Language)
companies.lang (30 - Price display format in the current language and currency)
11Stringadmin.lang (411 - String)
members.lang (105 - String)
12Intadmin.lang (416 - Integer)
members.lang (107 - Int)
13DateAndTimeadmin.lang (418 - Date and hour)
members.lang (108 - Date and time)
14Fieldadmin.lang (496 - Field)
blockedlog.lang (2 - Field)
exports.lang (62 - Field)
15Upgradeadmin.lang (1053 - Upgrade)
install.lang (110 - Upgrade)
16Serveradmin.lang (1064 - Server)
install.lang (55 - Server)
17DatabaseServeradmin.lang (1066 - Database host)
install.lang (58 - Database server)
18DatabaseNameadmin.lang (1067 - Database name)
install.lang (59 - Database name)
19DriverTypeadmin.lang (1075 - Driver type)
install.lang (54 - Driver type)
20CompanyNameadmin.lang (1096 - Name)
companies.lang (25 - Company name)
21WithdrawalsSetupadmin.lang (1597 - Setup of module Direct Debit payments)
withdrawals.lang (36 - Direct debit payment setup)
22Buyadmin.lang (1679 - Buy)
products.lang (56 - Purchase)
23Selladmin.lang (1680 - Sell)
products.lang (55 - Sell)
24AccountancyCodeadmin.lang (1683 - Accounting Code)
companies.lang (312 - Accounting account)
25CashDeskadmin.lang (1706 - Point of Sale)
cashdesk.lang (3 - Point of sale)
26ByDefaultInListadmin.lang (1865 - Show by default on list view)
categories.lang (85 - By default in list)
2LineIdaccountancy.lang (128 - Id line)
exports.lang (43 - Id of line)
4CustomerInvoicePaymentaccountancy.lang (220 - Payment of invoice customer)
banks.lang (104 - Customer payment)
5NotReconciledaccountancy.lang (283 - Not reconciled)
banks.lang (103 - Not reconciled)
28AffectedToagenda.lang (10 - Assigned to)
projects.lang (117 - Allocated to)
30Locationagenda.lang (16 - Location)
stocks.lang (34 - Location)
31InterventionSentByEMailagenda.lang (84 - Intervention %s sent by email)
interventions.lang (38 - Intervention %s sent by email)
33DeleteTypeassets.lang (29 - Delete)
members.lang (80 - Delete)
34ShowTypeCardassets.lang (32 - Show type '%s')
members.lang (148 - Show type '%s')
35IBANbanks.lang (32 - IBAN number)
bills.lang (442 - IBAN)
36BICbanks.lang (33 - BIC/SWIFT code)
bills.lang (445 - BIC/SWIFT)
37Accountbanks.lang (67 - Account)
compta.lang (15 - Account)
38SubscriptionPaymentbanks.lang (106 - Subscription payment)
members.lang (162 - Subscription payment)
39InvoiceRefbills.lang (325 - Invoice ref.)
receiptprinter.lang (67 - Invoice ref)
41NoSupplierOrderboxes.lang (72 - No recorded purchase order)
orders.lang (80 - No purchase order)
42ShowCompanycashdesk.lang (30 - Show company)
companies.lang (328 - Third Party)
43Historycashdesk.lang (69 - History)
suppliers.lang (6 - History)
45DeleteFromCatcategories.lang (78 - Remove from tags/category)
compta.lang (247 - Remove from accounting group)
46Customercommercial.lang (4 - Customer)
companies.lang (272 - Customer)
47Prospectcommercial.lang (6 - Prospect)
companies.lang (270 - Prospect)
propal.lang (12 - Prospect)
48ShowTaskcommercial.lang (18 - Show task)
projects.lang (39 - Show task)
50ContractStatusClosedcontracts.lang (9 - Closed)
products.lang (84 - Closed)
51ExportsAreaexports.lang (2 - Exports)
other.lang (266 - Exports area)
52ExportableDatasexports.lang (6 - Exportable dataset)
other.lang (270 - Exportable data)
53AvailableFormatsexports.lang (27 - Available Formats)
other.lang (267 - Available formats)
55CreateUserinstall.lang (66 - Create user account or grant user account permission on the Dolibarr database)
users.lang (30 - Create user)
66OrderDateorders.lang (10 - Order date)
suppliers.lang (9 - Order date)
67CreatedByother.lang (115 - Created by %s)
ticket.lang (157 - Created by)
68FollowingUrlAreAvailableToMakePaymentspaybox.lang (4 - Following URLs are available to offer a page to a customer to make a payment on Dolibarr objects)
stripe.lang (5 - Following URLs are available to offer a page to a customer to make a payment on Dolibarr objects)
69PaymentFormpaybox.lang (5 - Payment form)
stripe.lang (6 - Payment form)
70WelcomeOnPaymentPagepaybox.lang (6 - Welcome to our online payment service)
stripe.lang (7 - Welcome to our online payment service)
71ThisScreenAllowsYouToPaypaybox.lang (7 - This screen allow you to make an online payment to %s.)
stripe.lang (8 - This screen allow you to make an online payment to %s.)
72ThisIsInformationOnPaymentpaybox.lang (8 - This is information on payment to do)
stripe.lang (9 - This is information on payment to do)
73ToCompletepaybox.lang (9 - To complete)
stripe.lang (10 - To complete)
74YourEMailpaybox.lang (10 - Email to receive payment confirmation)
stripe.lang (11 - Email to receive payment confirmation)
75Creditorpaybox.lang (11 - Creditor)
stripe.lang (13 - Creditor)
76PaymentCodepaybox.lang (12 - Payment code)
stripe.lang (14 - Payment code)
77Continuepaybox.lang (15 - Next)
stripe.lang (17 - Next)
78AccountParameterpaybox.lang (19 - Account parameters)
stripe.lang (27 - Account parameters)
79UsageParameterpaybox.lang (20 - Usage parameters)
stripe.lang (28 - Usage parameters)
80InformationToFindParameterspaybox.lang (21 - Help to find your %s account information)
stripe.lang (29 - Help to find your %s account information)
81VendorNamepaybox.lang (23 - Name of vendor)
stripe.lang (31 - Name of vendor)
82CSSUrlForPaymentFormpaybox.lang (24 - CSS style sheet url for payment form)
stripe.lang (32 - CSS style sheet url for payment form)
83Stockproducts.lang (51 - Stock)
stocks.lang (18 - Stock)
84Stocksproducts.lang (53 - Stocks and location (warehouse) of products)
stocks.lang (19 - Stocks)
85Movementsproducts.lang (54 - Movements)
stocks.lang (23 - Movements)
86Suppliersproducts.lang (89 - Vendors)
suppliers.lang (2 - Vendors)
87ListOfStockMovementsproducts.lang (96 - List of stock movements)
stocks.lang (26 - List of stock movements)
88Unitproducts.lang (172 - Unit)
stocks.lang (41 - Unit)
95NewUserticket.lang (282 - New user)
users.lang (29 - New user)