Two instances launched from the same image do not get an IP

[Bobarshad]

I have two Images bionic-lxd and xenial-lxd. when creating two instances by attaching an internal interface from one of these images, just one instance getting IP.
+-------------------+---------+------------------+------+------------+-----------+
| NAME | STATE | IPV4 | IPV6 | TYPE | SNAPSHOTS |
+-------------------+---------+------------------+------+------------+-----------+
| instance-00000008 | RUNNING | 10.5.5.10 (eth0) | | PERSISTENT | 0 |
+-------------------+---------+------------------+------+------------+-----------+
| instance-0000000c | RUNNING | | | PERSISTENT | 0 |
+-------------------+---------+------------------+------+------------+-----------+

When making two instances from different image both instances will get IP and work.
+-------------------+---------+------------------+------+------------+-----------+
| instance-00000008 | RUNNING | 10.5.5.10 (eth0) | | PERSISTENT | 0 |
+-------------------+---------+------------------+------+------------+-----------+
| instance-0000000c | RUNNING | 10.5.5.8 (eth0) | | PERSISTENT | 0 |
+-------------------+---------+------------------+------+------------+-----------+

When attaching an external interface in every case using the same or different images it does not work, I mean none of them getting IP.
In all the above scenarios, the horizon shows everting it looks fine.