Is it possible to add multiple floating ip in 1 external network in Openstack?

Issue

• I have done to create multiple external networks, that's not what i want.
• I need a Instance which has two floating IP.

For example:
* There is a Instance, and i have two or more than two external networks, one of them is focus on website server,i can open the security 80 port.
* and another one is focus on control instance, So i just can open the 22 port, and as you know, if i want the instance can both has two external networks.