Thread:Project:Support desk/User account is not registered/reply (4)

I would have recommended the UserMerge extension as well. Whether you find something to automate this or not: You will have to create some kind of mapping, which tells you, after which rules accounts should be merged, anyway. Maybe you can automate a part of this operation, e.g. in usernames, you can replace all underscores with spaces. However, for upper- and lowercase differences (like in your "TW" and "Tw"), you will have to tell manually, whether it's the same user or not; I don't think there is a software-way of doing that - after all both of these names are different and valid usernames.