449m [2021-10-20 00:25:04.726] GPU2 Cpu verification failed. Share not sent to the pool. Rejected!
482m [2021-10-20 00:58:43.716] GPU1 Cpu verification failed. Share not sent to the pool. Rejected!
617m [2021-10-20 03:16:21.509] GPU2 Cpu verification failed. Share not sent to the pool. Rejected!
701m [2021-10-20 04:41:53.221] GPU1 Cpu verification failed. Share not sent to the pool. Rejected!
708m [2021-10-20 04:48:35.281] GPU2 Cpu verification failed. Share not sent to the pool. Rejected!
708m [2021-10-20 04:48:36.015] GPU2 Cpu verification failed. Share not sent to the pool. Rejected!
708m [2021-10-20 04:48:36.749] GPU2 Cpu verification failed. Share not sent to the pool. Rejected!
Are these messages an indicator that the Memory Overclocks are too high for these two cards?
Yes, but you can try a lower kernel number or increase the power. --lock-cclock is helping for stability as well.