Outside ASA has 172.30.8.1.
Is it possible for 2 different routers to nat a different IP to the outside interface of ASA firewall?
One router would have...
ip nat inside source static 172.30.8.1 220.127.116.11
and also have another router on a different providers circuit natting...
ip nat inside source statis 172.30.8.1 18.104.22.168
Yes it should be possible as each router will have independent NAT translations so there will be no conflict.
The NAT will work but whether it will achieve what you want is dificult to say without more details.