Many2Many fields are duplicating when adding the same record on proteus
Steps to reproduce:
- Activate account_invoice module
- Create a tax and set is as default account for revenue account
- Create a new invoice with a line using the revenue account.
- Add the tax to the line (which will cause a duplicate because it has been already added by on_change)
Current behaviour:
- A line with two taxes of the same record is created.
Expected behaviour:
- Like gtk client only one tax is related to the line (because the added tax is the same)