parallel

commensurate, proportionate

tantamount, virtual

allied, kin, kindred, relatable, related

approaching, approximating, close, coextensive, coincident, conformable, conforming, consistent, consonant, duplicate, equal, equivalent, identical, indistinguishable, interchangeable, me-too, redundant, same, selfsame, substitutable, synonymous, twin

entire, homogeneous, homogenous, unchanging, uniform, unvaried, unvarying

blend (with), conform (to), coordinate (with), go (with), harmonize (with)

complement, supplement

counterbalance, counterpoise

echo, image, mirror, repeat

add up (to), amount (to), approach, come (to), near

measure (up), partake (of), rival, suggest