Possibly you have more than one entity in Teamleader with invoices you want to import in Twikey.
Twikey can not make the distinction for which entity you import invoices, however it is possible to
import those invoices if you avoid using the same invoice-numbers.
Invoice numbers in Twikey need to be unique, if the same number already exist the invoice is not imported.
Teamleader construct the invoice number as fiscal-year with a number increasing for each invoice, for example
2023 / 1000.
For all your invoices, regardless of the entity the fiscal year will be the same by default. To be able to import
invoices from multiple entities ensure that the incremental number from one entity never overlaps with one of another entity,
or use a different prefix for each entity.