increase in pattern count while ATPG DFT

Can anyone suggest on my ques? 1) I had a netlist I generated pattern say 1000 count ,later I had next version of same netlist but if you see the ET generates 11000 patterns. Can anyone update the reason for increase in teh vector count? only-2 scan clocks 2-scan reset. 1st release say 10000 flops 2nd release say 10050 flops.