On the double eggs, i can also attest that a queen can and will lay more than one egg in a cell.
This last spring we bought 12 hives single 3/4 depth boxes, ten frames in each - all drawn comb and moderate supplies. Young queens in all and just started laying.
We SHOULD have got a second box on those hives a week after we got em - the farm was blooming and the girls were on their feet and running straight away.
Weather and work conspired - it was near four weeks before we got them those boxes. By which stage, 11 of the 12 were busting at the seams - queens laying areas were being badly compressed by honey and pollen, and there were two or three eggs in the cells in nearly half the hives.
Without sighting the queens (it was worse than standing room only - nigh on impossible to see them), I was satisfied that they were queen-laid eggs because of the circumstances, and because although there were multiples they were all laid in the BOTTOM of the cells of fully drawn comb, not on the sides, and not in the bottom of short cells - ie, the girl that laid em had to have a loooong body.
In your circumstance I'd also think you're correct in that they are queen laid.