Yup similar situation here
Cast a Glitterdust spell, but scult it (feat) into the "4 columns" area of effect option.
Now overlap the columns so that 2 or 3 or 4 of them impact/cover the same bad guy.
How many will saves does the bad guy make?
If you are in 2x the spell's area of effect, does it make a difference?
Do you save 4 times, or make 1 save at -4, or just 1 save period?