Ab rio

When using RIO and block transfers within PLC5. Is it possible to use two HMIs on this network, using the same data. Each HMI would read the same data from the same BTRs and would write the same data with the BTWs.

Possible? That depends on the HMI. But you realize that by adding additional devices to the RIO you will be affecting the speed of the RIO. Do you really want to slow down the RIO?

Instead, put your HMIs on the DH+ where they can read whatever data they require, including the BTR/BTW data without impacting the RIO performance. Your PLC-5 already has DH+. That's what it's there for!

OG

To answer the specific question, then no it is not possible to use the same BTW and BTR blocks, because these address specific RIO rack and group numbers that are assigned to the particular HMI.
However, you can easily copy the BTW and BTR blocks and simply modify the RIO rack and group addresses in the copied blocks.

Apart from that, I totally aggree with OG. It not only slows down the i/o that is on RIO, but is also awful to program in the HMI.
If you can, put the HMI's on DH+.