Is there any evidence for "altercate" ever having been pronounced with stress on the second syllable?
Samuel Johnson’s dictionary of 1755 has no entry for altercate, but tantalizingly does have one for the verb alternate, where he indicates the stress on the second syllable (like alternative), adducing a citation from Milton where the meter suggests that pronunciation. The entries for the adjective and noun are also instructive.
Thomas Dyche’s spelling dictionary of 1737, however, shows Johnson’s pronunciation of alternate, but an accent on the first syllable for altercate:
