500 lbs is a big load for a 14 foot tandem canoe. I suspect it would leave very little freeboard. Freeboard is the height of the top of the gunwale amidships for any given canoe and load. This will depend on the buoyancy of the canoe, the load, and the depth of the canoe at center. I am not familiar with this particular canoe so I have no idea of what the depth at center might be…
Some canoe makers list a “6” freeboard capacity". This is how much weight the canoe can be loaded with still leaving six inches sticking out above the water. This spec is really intended only for comparison of buoyancy for different canoes. Very few experienced canoeists would load their canoes that heavy and attempt to paddle them. Six inches of freeboard leaves very little room for error. Even assuming the water is completely placid (no waves or boat wakes) it would take only a mild inadvertent lean of the hull to dip a gunwale under. That can happen pretty easily in a tandem canoe if one or both of the paddlers makes a quick and unanticipated shift in weight.
I have no idea what the 6" freeboard capacity of this boat might be. But I can give you a figure for another 14 foot tandem canoe. The Mad River Winooski was/is a 14 footer with a beam of 39" that had a 6" freeboard capacity of 900lbs. But the additional 3 inches of beam amidships, even though it does not sound like that much, would add a very considerable amount of buoyancy. The Winooski was also a fairly deep canoe with 14" depth at center. If this canoe is not as deep, the freeboard would diminish by 1" for any given load for every inch less than 14" depth.
My guess is with a 500 lb load in this boat you would be pushing 6" of freeboard. Could you and a friend paddle it safely with that load in perfectly calm water? Perhaps, but another consideration is that a boat overloaded to that degree is going to sink way down in the water. It will draw a lot of water and easily hang up in shallows. And it will have a great deal of drag and paddle like a pig.
If you anticipate a 500 pound load in a tandem canoe, I think you need to look for a boat longer than 14 feet.