Steps to reproduce:

1. Create two a template with LLD SNMP discovery and a bunch on item prototypes
2. Create a host with 2 SNMP interfaces where the only difference is the SNMP community
3. Bind the previously created template to the just added host
4. Set the SNMP LLD discovery to use the secondary host's SNMP interface and nopt the first one

Result:

The discovery is correctly being sent over the device with the correct SNMP community.

The item prototypes are being associated with the first available SNMP community and not the one inherited from the SNMP LLD discovery.

Moreover, opening the item prototype "test" popup we see that by default the SNMP community selected is the first available on the host and not the one inherited from the LLD SNMP discovery. Doing a tcpdump on the host sending out the SNMP request we can clearly see that the used SNMP community is the wrong one.

Expected:
The discovery is correctly being sent over the device with the correct SNMP community.

The item prototypes are being associated with the same SNMP community set from the SNMP LLD discovery.