I would just pick one, say A , and do all pair-wise comparisons with it.

all(sapply(list(B, C, D, E), FUN = identical, A)) # [1] FALSE

Remove the all() to see the not identical one(s)

sapply(list(B, C, D, E), FUN = identical, A) # [1] TRUE TRUE TRUE FALSE

identical ought to be transitive, so if A is identical to C and to D , then C should be identical to D .

(Thanks to @docendo discimus for simplified syntax.)