Pjiang and Xiao Baitu please help

I moved to a new emplyer using my EAD card, but I am still working part-time for my I-140 employer. I asked my old employer to update my I-9 Form using my EAD. They asked me to write it was my decision to use EAD in order to withdraw my H-1B (I was using H-1B for my old employer). Will it be a problem since I am using my EAD for the new job, but my old emplyer haven't withdrawn my H-1B?