The New England Patriots won Super Bowls in 2002, 2004 and 2005.
The correct way to express this is "Three championships in four years."
The incorrect way to express this is "three-peat."
I am sure Tampa Bay would be quite irked to hear that their 2003 win somehow doesn't count.
PS: Oh, and "Dynasty" was a show starring John Forsythe and Joan Collins. Hope this helps.
PPS: Actually, the incorrect way to express anything is "three-peat" because it's incredibly stupid, even when appropriate.
PPPS: You knobs.