Yes, it may be possible to use different SMRTs unless TPX is defined as a VTAM Generic Resource then all TPX started tasks must use the same SMRT.
If TPX is defined as a VTAM Generic Resource then all TPX started tasks must use the same SMRT.
It may be possible for multiple TPX started tasks in a sysplex to use different SMRTs* as long as none of the SMRTs conflict with each other in obvious ways. For example, you could run into trouble if one SMRT specifies FASTPATH = YES and another to use NO.
If some TPX started tasks defined with the same generic resource use different SMRTs, you may see this error:
TPX5556 CA-TPX SYSPLEX SERVICES FOR NODE(vtamnode) are disabled
*SMRT = System Options Table, historically known as Session Manager Resource Table