Tow public IP's with one GW

looks like your ISP gave you a /30 subnet. That is 4 usable IPs then.

Looks like they gave you 10.10.10.0/30 with 10.10.10.1 as Gateway.

That means:

10.10.10.0 - network address

10.10.10.1 - gateway

10.10.10.2 - Firewall

10.10.10.3 - free

10.10.10.4 - free

10.10.10.5 - broadcast address

So if you need 10.10.10.2 or .3 on the FGT for something you would have to set them up as secondary ips on the interface that has 10.10.10.2 as primary ip and is connected to the router. Then you can create some policy,vip,... for them.

Alternatively you can set them up as secondary ip on the router and do some portforwarding there if needed.