i have a plugin that failed during setup;

a refresh of the failed page resulted in two of the same instances added to plugin section;

when trying to uninstall these i get an error - "EX1091 Something went wrong. Please try again."

any way to manually remove the offending plugin's?

Submit a ticket and I'm sure someone from T2 would be able to help. I wouldn't approach doing that unless it was a local test install I could wipe if need be, and I know what I am doing... so... ensure you have a recent backup before they proceed.