Your phone can have two IMEI numbers just only if it's dual-SIM. Then it has two modems (practical one but is registered to two networks) and thus two registration to network. For each registration needed is a unique IMEI. Remember about the difference:
dual SIM device which means both SIM cards can be connected to the network at the same time means your device has two IMEI numbers,
two SIM device which means only one SIM card can be connected to the network at a time means your device has only one IMEI number.