For the Tour:Consecutive days. And I mean either way TT-MTF or MTF-TT.
Armstrong in 1999, 2001 and 2004 (three in a row).
Ugrumov in 1994.
Hinault in 1979.
Merckx in 1970.
EDIT: Sorry, read it as mountain stage at first, not MTF. Only Armstrong in 1999 and 2001 then.