HELLO SOHAN
Well if you are confident that you will get seat into your desired institute with KCET than no need of writing COMEDK but there is a n alternate chance since the cutoff for comedk is high and getting a seat through COMEDK quota is easy but the on;y disadvantage iis you will need to pay twice the amount which you you have been paying for KCET.
Getting good colleges KCET is little difficult since there is aggregation of boards+KCET marks. so that why the cutoffs are also in 1000 for good colleges
but in COMEDK the rank is dependent on COMEDK marks only!!
the more no of exams you give the more no of options in your hand if you perform well
HOPE IT HELPS!!