Workers are simply underdeveloped queens. They have the ability to lay eggs, but they can only lay unfertilized eggs - which turn into drones. If a hive is without a queen for more than 3 weeks some workers will begin laying eggs. It is usually pretty easy to identify. Workers do not have the ability to control how many eggs they can lay. Their will be multiple eggs and on the cells walls. (They are usually not long enough to reach the very bottom of the cell) You will find drone brood all over the frames and in worker cells. The brood pattern will be very bad (shotgun pattern) and probably unhealthy looking. New queens will occasionally lay more than one egg in a cell. However, you will be able to tell the difference because their will be lots of worker bee brood.
If your hive has been queenless this long, they will very likely not accept a new queen. You have several options. You can add several frames of brood covered in bees from a different hive and place a new queen (in a cage) between them. You can also combine the old hive with a new one. If your are unable to get a queen within a week. Supply the hive with several frames of brood to hold it over till you can get a queen. If you give it enough frames of brood and bees they may be able to successfully raise their own queen.