Whatever column as the source file name you describe (Source File?), highlight and duplicate it to the Lab roll column. Edit out the extra stuff from the names. If there are a lot of clips you can batch process in a text editor:
Exports master clips as an ALE file with Start, End, (Tape or Source File) and Lab Roll.
In a Text editor, edit out the extra stuff at the end of the name in the Lab Roll column.
Merge ALE back in.
Link to original camera files and highlight them
Highlight sequence
Right Click sequence and select “Relink”
Use relink to selected
Set up to have Lab Roll on source clips and “Tape/Source File” on sequence
Click OK
Michael