What movie was playing in the theater Lee Harvey Oswald ducked into after he and others shot John Kennedy?

It was a double-bill. Most sites say it was "War is Hell".

Following the horror in Dealey Plaza accused presidential assassin Lee Harvey Oswald (1939-1963) slipped into Dallas’ Texas Theatre without paying, immediately alerting authorities. A double feature was playing that day, "War Is Hell" (1963) starring Baynes Barron and Michael Bell and "Cry of Battle" starring Van Heflin and James MacArthur. The former was a Korean War film while the latter was set in the Pacific during World War II. The nervous Oswald, however, was unable to watch much of the twin bill as he was quickly arrested by Dallas Police following a brief, violent struggle.

https://en.wikipedia.org/wiki/War_Is_Hell_(film)

Booth shot Lincoln in a theater and was arrested in a warehouse (barn).

Oswald shot Kennedy from a warehouse and was arrested in a theater.

Both were succeeded by Johnsons (and not in the WSB sense).