Whenever a customer orders a new IP address for a VM, the new IP address becomes the default one. Newly added IP address is assigned to the eth0 interface instead of eth0:1 alias (or eth0:2 and so on).
This happens only if the new IP address is less than the default one (say, 126.96.36.199 is less than 188.8.131.52).
Such behavior was classified as the software issue PBAS-29971 and was fixed in OBAS 4.5.5.
To resolve the issue, please upgrade to 4.5.5 as described in How to upgrade OBAS system to the latest available version.
Workaround for 4.5.4
For CentOS/RHEL x64
Download the hotfix hspc-pserver-4.5.4-22.swsoft.x86_64.rpm and install it by running
# rpm -Uhv hspc-pserver-4.5.4-22.swsoft.x86_64.rpm # service hspcd restart
Warning Restart of the hspcd service will cause OBAS downtime for about 10-60 seconds.