Webclient - Controlled field changes result in duplication of data

webclient 3.0.6

Reported from one of our many catalogers:

Added the 800 field to include series information. Added the authority and pressed Ctrl + D to add a new subfield. The selected subfield duplicates multiple times and removes the authority field. If I undo it by using Ctrl + Z, it reverts and I can add the $v with no issue.

Confirmed by local cataloger:

Once the field has been controlled, I can't go back and add another subfield without it completely messing up the entire line. Essentially, she's adding the 800 $a and $t and then she's applying the authority record which adds the $0. However, when she goes back to add the $v, it applies the series name in $t to both $a and $0. It definitely should not be doing this.

Attaching screen shot showing duplication data in the 800 field