The Prisoner of Zenda (1979)
In order to save King Rudolph of Ruritania from assassins and murderous usurpers, the kingdom hires a look a like London cabby to impersonate the Monarch
Schizo (1976)
A newly married woman becomes convinced someone from her past is stalking her, but nobody believes her until the bodies start to pile up
Phase IV (1974)
Desert ants suddenly form a collective intelligence and begin to wage war on the inhabitants It is up to two scientists and a stray girl they rescue from the ants to destroy them