In exports file, you will mention a single IP or special character for full access. To give only access for two IP mention it separatly as shown below.

Here, 192.168.1.2 and 192.168.1.3 as two IPs

/Folder-to-share 192.168.1.2(rw,async)
/Folder-to-share 192.168.1.3(ro,async)

192.168.1.2 has both read & write acces

192.168.1.3 has only read

once its done, restart nfs service and execute exportfs -a command