There can be a difference in bi-amping but as
@larkone has said it's not as simple as connecting two amps to the speakers there has to be a power and gain balance. However it works with high end speakers and the Missions will not gain that much even with bi-amping. Manufacturers put four binding posts on speakers more as a marketing play rather than any real audio benefit.
If I had a pair of speakers costing over £2000 I'd consider bi-amping, sadly I don't and my speakers perform perfectly with a single wire. The Marantz is a classy amp and will take a significant upgrade in speaker quality but a nice system to get you started as it stands.