Thanks for reaching out with this beekeeping question.

Here are a few possible explanations to what you are observing:

1. Sometimes queens do lay more than one egg per cell. I've most often seen multiple queen-laid eggs in colonies with new queens that just started laying, especially colonies with little drawn, empty comb (such as a package hived on foundation).

2. Even though queen and brood pheromones suppress worker ovaries, sometimes there can be rogue laying workers even when the colony is queenright. There may be a small patch of worker-laid eggs in a hive that otherwise has queen-laid brood.

3. Sometimes laying worker colonies build what appear to be queen cells but actually do not have a queen developing in them. Upon opening the cells that look like queen cells, we often find drone larvae/pupae inside of these cells. If you were also finding the presence of drone brood in the larval and pupal stages and an absence of worker brood, then this scenario makes the most sense.

If you aren't sure what's going on because you find multiple eggs in some cells but there isn't yet the larval or pupal stages, it may help to just close the hive and return a week later. Once the hive has older larvae and sealed brood, it's easier to tell if the brood is worker brood from a queen or drone brood from laying workers.

It's not a guarantee, but we do expect colonies to usually kill a new queen if there are laying workers.

Happy beekeeping!