Masteries Name Bug.

This is a simple, bug, that happened when I have made a masteries page. I've had a page named "YASUO" and then, I have made another one named "Yasuo". It did not stop me from making it, but when I got in game I had no masteries. After the match was finished I have got error messages each time I tried to click on a mastery page, until I have found the problem. Was this a one time incident?