not very randomized

I tried 10 GO on your demo page http://primaryschoolict.com//random-name-selector (50 names in the list), 3 times (refreshing the page each time). But the algorithm only selected 16 different names in the whole process, 4 of them twice in the same serie. I think the engine needs some randomizing improvement.

Anthony Williams x x
Barbara Martinez
Betty Walker
Brian Cooper x
Carol Green x
Charles Carter
Christopher Brown
Daniel Campbell x x
David Roberts
Deborah Perez
Donald Scott x
Donna Roogers
Dorothy Cox
Edward Adams
Elizabeth Carter
George Phillips
Helen Mitchell
James Smith x
Jason Anderson
Jeff Nelson x
Jennifer Parker
John Wong
Joseph Baker
Karen Martin
Kenneth Stewart
Kevin White
Kimberly Allen
Laura Miller
Linda Harris
Lisa Patel x x
Margaret Turner
Maria Morris
Mark Clark xx
Mary Wilson x xx x
Michael Robinson x
Michelle Taylor xx x
Nancy Jones x xx
Patricia Thompson x
Paul Jackson
Richard Evans
Robert Moore x x
Ronald Lee x x
Ruth Sanchez
Sandra Collins
Sarah Garcia x
Sharon Reed
Steven King
Susan Wright
Thomas Bell x
William Young