The software is just weird. For some odd reason it wants a "first" name and a "last" name separated by a space. The concept of a single identifier doesn't exist here. So to be happy, it inserts a space after the name and then REPEATS the name again.
If in your example, Mr. "XYZ1234" were to enter a space in his ID to show as "XYZ 1234", the the repeated value would disappear.
There might be a good reason for this, but I really doubt it as the FamilyTree site, the GetSatisfaction forum for FamilySearch site, and even the church sites which all share this value, do not treat it this way.