The Xbox and Gamecube have the EXACT same number of million sellers. 38

http://vgchartz.com/worldtotals.php?name=&console=XB&publisher=&sort=Total

http://vgchartz.com/worldtotals.php?name=&console=GC&publisher=&sort=Total 

they both almost had the same userbase

not surprising given they had almost same userbase as pichu said

The Xbox topped out at roughly 3-4m more than the Gamecube, and it had a tie ratio of about 11 to 9.5 for the Gamecube, so it is kinda surprising.

The GC had 10 million more sold in those million sellers however. I am going to guess it is because it had 4 games over 4 million and the Xbox had just the Halos... besides the Halos the best sell Xbox game was Splinter Cell coming in at 2.7 million or so.

Well, thats not bad for a no reputation system to stick with and Old school well known name at the time. Gamecube was a great system with some really good franchises on it. Actually, i gotta admit, i miss my gamecube, hahaha.

That's not to weird.

Doesn't surprise me. Gamecube and Xbox essentially tied.

well, they sold almost the same # of units so quite expected

Just coincidence. It´s a tie on the last generation.