I have a round about solution for dealing with sequences in scene mode.
Before importing the first one sequence save filename.an8 AND "SAVE AS" filename_b.an8.
Import the 1st sequence and check that everything is the way I planned.
Save filename_b.an8 AND save "AS" filename_c.an8
Import the 2nd sequence
....... etc.
That way only the last used copy may have ONE sequence which is incorrect and should be deleted and that'is no problem.
Close the file, delete the file and restart with the previous version (i.e. _b.an8, _c.an8, etc)
When all is done, delete files filename.an8 and all _extensions and continue using the last version.
It's not really as cumbersome as it sounds, it's only a matter of not forgeting to save and save as before moving to the next sequence.
Though all that said, I wish we could just delete a sequence in scene mode and start again.