Why should it be possible to carry across multiple marriage events via the source linker?
In other instances, we are encouraged not to add detail at this point, but rather to get back to the Person page and evaluate the data from there. Indeed, if there are already inputs (in say the christening or burial fields) further data cannot be carried across.
I don't see why it should be made easy to add multiple events to the Couple Relationship section by this means, regardless of whether the date is the same as already inputted (as in this case) or not. On several occasions I have found the data to relate to banns or a marriage licence and carrying the earlier date across means the wrong event gets to be displayed on the Person page.