thePeerage.com

[col48]

There's a little hole in the succession of Earls of Moray

On the database, there is
Thomas Randolph 1st Earl d 20 July 1332 (person 213514); his father was also Thomas Randolph (213518)

There is also on the database
John Randolph (3rd Earl) among the children of the first Earl.

However, there was another TR, son of the 1st Earl, who was (briefly) the 2nd Earl
Thomas Randolph was killed at Duplin Moor 11 Aug 1332 fighting Edward Balliol, according to this source:

http://fmg.ac/Projects/MedLands/SCOTTISH%20NOBILITY.htm#_Toc268450043

If you have not come across the fmg site before, it is well worth looking at; their brief is AD500-1500 especially the first half of that period. It is based in Canada and quotes sources very extensively and carefully.
I'm not sure of the copyright position if you want to use data in bulk, but twas ever thus.