A recent question was posed on our facebook operator group.
What will happen if I have two unique IMSI with the last four digits are on the same eNB in NAT mode? Will I be able to access the UE behind it? Short answer is: No. You will need to have a different IMSI on one of the UE to avoid such conflict.
This unlikely issue is avoided by running Bridge mode or using hosted EPC whereas each UE will have a unique public IP address for remote access.