Tents can have 1 or 2 doors. Of course, there are tents with more doors, but these are not so used.
Tents with 1 door
Models with a single entry have the advantage of a lower price compared to those with 2 entrances. This means for the one single piece: 1 zipper and a cut less, and for those with two pieces: 2 zippers and 2 less cuts. Otherwise there are only disadvantages.
Firstly, in the case of these models, you will not be able to stay inside during the summer days, if the tent is placed in the Sun. Secondly, to get out, you will have to get roll over those who are closer to the exit than yourself. Thirdly, sometimes for better night airing, you’ll have only one door for ventilation. Also, condensation, an unwanted phenomenon, can occur more easily.
Tents with 2 doors
Models with 2 doors have much better ventilation. This means that you can sit in it in the hottest days the summer, even if you put it in the Sun. The trick is to open those 2 doors to make ventilation.
These models are a little more expensive. However, when you buy a tent, you should not look at how much you pay in addition for one or two zippers. More important is that you can use it well, as much as possible and get you comfortable whatever the weather conditions and camping.
The extra comfort offered by the tents with 2 entrances in the summer and makes them the main choice in preference to models with a single entry.