It was long before I played Bard again, but I remember that when I activated Simulacrum from Vhailor's Helm, used Mislead scrolls from both Bard himself and the Sim image, then sang the Bard songs from all four characters their effects should stack.
It's always +4 (EBS) now no matter how many images are singing. I also tried Skald songs, same issue.
I’m running BGIIEEv2.3 with cdtweaks, SCS, Ascension, UB, Almateria’s Restoration and several quest mods installed, but I've traced the installation process carefully and I didn’t recall having anything checked for Bard Song, Mislead Images. Has this exploit been patched? Insights, thanks~~