I wouldn't worry. I think it is just to keep them with the cam lobe that they had worn with. It isn't a weight thing unless the engine is completely balanced.
'88 Widebody E30 track car (M54 swap in progress - it blew up. . . M52 swap in progress)
'00 E39 Touring with a manual tranny
-Both with inline 6s the way God intended-
'86 Toyota MR2 for ice racing