Odd display of users in back end

Have just started doing something for a client with their membership list, in a website developed by someone else.

In the user area there is a very odd display see image in link
click here

Anyone come across anything like this – they have s2Member Pro installed that they are using to manage their membership list.
I am going to ask them as well

And yes will be updating once have tested this on a clone of the site as this is the first time I have accessed this site

thanks