In Notes 8 and beyond, IBM has created new verifications such that you can no longer have two groups with the same name, even if one is ACL ONLY and the other MAIL ONLY.
I’ve found the Verification Code that they use to check for unique names. But the code doesn’t take into consideration would group type your creating. I can not see any harm in having two groups with the same name, one being set to ACL ONLY, the Other set to MAIL ONLY. Can anyone else? Has anyone altered there verification code with success?