Deduplicatin using equivalence groups
deduplicate_equivalence(pairs, var = "duplicate_groups", selection, x)a pairs object, such as generated by 
pair_blocking
name of the variable to create in x that will contain the
group labels.
a logical variable with the same length as pairs has
rows, or the name of such a variable in pairs. Pairs are only 
selected when select is TRUE. When missing 
attr(pairs, "selection") is used when available.
the first data set; when missing attr(pairs, "x") is used.
Returns x with a variable containing the group labels. Records with 
the same group label (should) correspond to the same entity.