Tandem axles on a 5x10? That sounds awfully small. The smallest I think I've seen tandems on before is a 6x12, other than equipment trailers (generators, water, etc). That said, as long as the trailer is well built, it should handle mild off roading, and conceivably give a little better break-over and departure angles. But the tire scrub and weight will probably make it pretty difficult offroad.
On road, it will probably handle just as well or better than a single axle. Regardless of load, I will often pull my tandem axle 7000lb 6x12 instead of my 2000lb 4x8 trailer just because it rides better and has brakes.
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