Can there be several representative certificates in the same company?

Yes. The same company (same VAT ID) can have several active Representative certificates at the same time, as long as they are in the name of different natural persons (i.e., different proxies).

What we do not recommend is sharing the same file and password among several partners, since the digital signature carries the same legal responsibility as a handwritten signature, and it would be impossible to deny who executed the action.