Work permit renewal and new work permit with in the same time

Hello everyone,

I am new to this group. i am not sure i can ask this here , still trying.
I am working in Leuven for a known technology company in semiconductors as a consultant.
Am here in Belgium for almost 1 year.

My work permit for the coming year is ready and it is available in Townhall.

At this time, i received an offer from other company and the process is going on.
They will apply new work permit for me.

My question is,
1. Do i have to collect the work permit from my present company and go with resident card process?
2. Or wait for new work permit from new company.
3. If i don't collect the work permit from my present employer, is there any problem?

My current resident card is valid for ~2 months.

Any one knows about this, please let me know.

Thanks & regards
Manu