As requested by OP, below is my comment expanded into an answer.
Avoiding multiple characters with the same name seems to be a common technique in writing. George R. R. Martin said in one of the interviews:
But I broke a lot or rules in writing these
you're taught as a writer, that I certainly was taught. But at certain
point I thought, "To hell with those rules."
Well, having so many characters, for one. Having similar names. Stuff
like that. I remember as a little baby writer I was taught never have
two characters whose names begin with the same letter because people
will get them confused. And I realized I was going to have more than
26 characters, so that would have to go out the window.
And also I was reading a lot of history. [People said], "Never have
two characters with the same letter? Certainly never have two
characters with the same name." But then I'm saying, "That's so
unrealistic." I mean, English history is entirely composed of Henrys
and Edwards. There's endless Henrys and Edwards, and you know, not only kings, who at least get numbers, but the guys who never become king. They're princes, and then they die. They're not even distinguished by numbers and it's very hard to keep all these guys straight. But that's the way the history actually was. Families using the same name over again. And I like that element of verisimilitude, [so] I adopted that.
However when Martin's saga got adapted into Game of Thrones its writers decided to follow the rule and introduced several name changes to avoid viewers confusion.
This question deals entirely with one such change:
- Real name of one character (unknown until one of the later seasons) has been changed from Walder to Wylis to avoid confusion with already existing character Walder Frey
Other examples (thanks to user568458's answer to the abovementioned question) are:
Robert Arryn has been changed to Robin Arryn as two more important characters were named Robert and Robb
Asha has been changed to Yara as it was too similar to Osha, an already introduced character