Does old approved I140 loose its PD if it is used for a new I140 with another employe

Folks

I seriously need to know about this. I had tried to pose this question on lawbench, but could not get answer from a lawyer. I have an approved I140 in EB2 from employer A. I left him and joined a new employer B since last 2 years (I am post 6 years of my H1B). Now employer B is in the process of filing my GC and plans to use the PD from ols approved I140. However I am still banking on the I140 of my old employer A because, employer B will not maintain my GC application if in case I quit the company and go to Canada (which I plan to do soon). While employer A will still support me in this and will continue my GC application. The question I have is this. If and when my I140 with employer B gets approved (using the PD of old I140 from employer A), will it impact my I140 from employer negatively. I.e. can the old I140 still remains valid and the PD date for the old I140 still remains valid. Or is it that since I used that PD for new I140 from employer B, I loose that PD for the original I140. Please let me know about this, because I am really confused about this. Because it is only my old employer (a small good desi company) will support me if I go to Canada. The new employer (a big American vendor) will immediately suspend my application the day I quit from here and move to Canada. Please let me know. Really appreciate the help.

Thank you.