When copying instead of creating a new OpcUa Driver tag, it looks like changing the used client certificate for one of the copies does this for all of them.

This seems like a bug or am i missing something.

When a tag is copied, all the parameters will also be copied and in the case of an OPC UA Client Certificate this will usually copy the certificate "Friendly Name".

If you have multiple client certificates then give each one a different "Friendly Name" and set that name in the driver config as appropriate.