LTE: How does PGW handle DHCP messages exchanged between UE and DHCP server for two different APNs ?

Question

Here assumption is PGW serves both the APN and UE will get IP addresses for both the default bearers using the DHCP server.
I am not sure, DHCP messages for both the PDNs will be transmitted using the first default bearer or DHCP messages for each PDN will use its associated default bearer.
Case 1 :
IP addresses for both the APN assigned by same DHCP server

Case 2:
IP address for each APN assigned by different DHCP server.

In both the cases, I want to know how PGW will deal with DHCP message and also on what basis a particular IP will be associated with a default bearer at UE if its uses same default bearer for the DHCP message exchange.