Can i plau marching order to different battlefield with repeat

Yes. Repeat lets you make fresh choices for the additional execution, so the second "fight" can involve entirely different units at a different battlefield.

FAQ #719 uses exactly this card as the example: you could target unit A to fight enemy unit B at one battlefield for the first execution, then unit C versus enemy unit D at a different battlefield for the Repeat (Rule 820.2.a — choices for the extra execution need not match the first).

Two things to remember: all targets are chosen during finalization, before anyone can react, so your opponent sees both fights coming; and Marching Orders' friendly unit can be "anywhere" (Base or battlefield) while the enemy unit must still be at a battlefield for each execution.