ClearAll[labelings, labelingFreeCanonize]
labelings[a_] := Module[{u = Union @ a}, a /. Map[Thread[u -> #] &] @ Permutations[u]]
labelingFreeCanonize = First @ Sort[canonize /@ labelings[#]] &;
Union[labelingFreeCanonize /@ t]

FWIW: Alternative ways to canonize:
1. Permute input list under the elements of CyclicGroup:
ClearAll[canonizeCG]
canonizeCG = First @ Sort @ Permute[#, CyclicGroup[Length @ #]] &;
2. Use Ordering @* Ordering to get the ranks of list elements instead of Position in @Mr.Wizard's canonize:
ClearAll[ranks, canonize2, canonize3]
ranks = Ordering @* Ordering;
canonize2[a_] := ranks[a] // Map[RotateLeft[a, # - 1] &] // Sort // First
or
canonize3[a_] := ranks[a] // Map[RotateLeft[a, #1 - 1] &] // #[[First@Ordering[#, 1]]] &
All three methods give the same result as canonize:
canonize /@ t == canonizeCG /@ t == canonize2 /@ t == canonize3 /@ t
True