You can create a multi-photo upload contest and give participants the option to submit multiple photos.
You are organising a photo contest and would like participants to upload more than one photo? You'd also like those photos te be displayed in the gallery?
It's possible, you just need to add an upload question after the initial one. This question can either be required or optional.
In the main gallery, you'll only see the first picture.
If you click on one picture, you'll then be able to watch the other participation.