I haven’t tried this and I do not own a second KrakenSDR for testing.
See Carl’s hint here: How to run two krakens simultaneously on one computer?
Carl suggested to run two Hemindalls on a single Raspberry.
However your schematic is different. If you run two Heimdalls on two Raspberrys then you will have to install a slightly modified version of Heimdall on the second Raspberry. It differs in the IP address under which it is accessed by GNU Radio. For this purpose you will have to manually modify the Heimdall Python code on the second Raspberry, defining a separate IP address both in the Heimdall Python code of the second Raspberry and correspondingly in the second GNU Radio KrakenSDR Source block on your Windows. The port addresses of the second Heimdall and consequently of the second KrakenSDR Source block may remain the same (5000 and 5001).
As the two KrakenSDRs are not synchronized by a common Heimdall, they will provide two separately coherent five-channel streams. But the two streams will not be coherent with each other.
Even if they were: If you receive these two streams in GNU Radio with two separate KreakenSDR Source blocks, then the result in GNU Radio would not be a ten-channel coherent stream because GNU Radio runs any blocks in separate Windows threads of the same GNU Radio Windows process. Therefore GNU Radio will run the two KrakenSDR Source blocks in two separate Windows threads (which should basically work). However, as the two blocks will be executed sequentially as threads and not in true parallel, the KrakenSDR channels within each block will remain coherent but not the two KrakenSDR Source blocks with respect to each other.
Conclusion: Your setup should work with the above mentioned IP adaptation. But coherence among all ten channels would require significantly more effort.