I have the same amount of ETH incorrect shares dual mining with v11.4 as before over two rigs, at most 1 or 2 per 1000 shares on Nanopool. If you're getting more incorrect shares with v11.4, if probably means your settings were too high to begin with or a Bios mod with too aggressive timings. Use HwInfo to check for memory errors and adjust the memory clock down by 50 MHz until there are no more errors.