Editing comsol file on older one does it affect the result?

I am designing patch antenna for the various substrates. I am getting confuse about simulations when I edit my previous file and when I make new file for the same substrate with same mesh control, S11 results are getting different values,suppose previously edited file gives s11 -7.45 and if I make new file for the same substrate that I edited in the previous file which gives s11 -6.423.Why is it happening?
Please advise me about it.

Kind Regards,
Sachin Pandure