Because of the different NETMASK, I'm wondering if I put the two servers in the same Switch, will this be ok?
No, using different subnet masks does not stop an IP conflict. there are basically two possible outcomes.
Some IP stacks do a check for duplicate addresses before bringing the interface up, others don't. If the device that comes up second does a duplicate check then you end up with one system working and the other not. If (due to a lack of duplicate checks) both interfaces come up then which server traffic gets sent to becomes unpredictable leading to troubleshooting nightmares.
If your switch has management features then you can split the devices onto seperate vlans. This will stop them conflicting with each other, but will also mean there is no direct path between them.
It is possible to build a NAT box to allow them to communicate, but it's tricky because most NAT implementations don't handle overlapping address spaces. This typically means if you want to make two servers with the same IP talk to each other you have to NAT the traffic twice with two separate instances of the NAT engine.
Note that two separate instances of the NAT engine does not necessarily mean two separate hardware devices. For example modern Linux kernels have a feature called "network namespaces" that allows multiple separate instances of the network stack (including the NAT engine).