Hi Julia,

I know this is an old forumpost, but we just started working with Odoo and came across this same issue.

We have a few different companies as customer who share the same bankaccount from which they pay us. We have also companies which are customer and supllier and as such have the same backaccount. This is in Odoo impossible it seems. In Odoo 11 and also in Odoo 12.

Did you find a work-a-round for this?

I found a discussion on github:

https://github.com/odoo/odoo/issues/15636

I don't completely understand the conversation, but I see that Odoo doesn't want the bank account number to be used more than once. 

I agree with the discussion that it would be nice though, most accounting software doesn't have this limitation and is thus better suited for B2C companies with a desire to use f.e. Direct Debit.