Etymology of 若 vis-a-vis 如果
It's not likely that 若 is a contraction of 如果, because 若 came first by a thousand years or so.

Nor is it likely that 如果 is a splitting of 若, because 果 is real. Long before 如果 there was already 若果, and before 若果, 果 was already grammaticalized to mean "ultimately" ("bear fruit" -> "ultimately", see 果然, 果真).

So 若果 was a legitimate, intensified version of 若. As for how 若果 became 如果, we can speculate that it was an easy phonetic and etymological transition: 如果 [nja kojʔ] and 若果 [njak kojʔ] would have sounded almost identical even before the loss of stop finals post-MC, and 如 ("follow" -> "compares with/likens to") and 若 ("obey" -> "as if/if") are grammaticalized in similar, if subtly different ways.