Unknown Spotting ( One Snail, Had Two Shells, Growing Together, As One Shell )

Description:

About one and a half weeks ago, I spotted one snail, resting on the left side of the bottom step, that goes to my house. What I Saw - This snail, had two shells, growing together as one shell. I saw this, with my own two eyes. My photos came out very bad, because I was in a hurry, and also, the lighting was bad. Again - I saw a snail, that had two shells, growing together, as one shell. Again - All my photos, came out very bad.

Habitat:

I spotted this snail, resting on the left side, of the bottom step, that goes to my house.

Notes:

Around one and a half weeks ago, I was taking some photos, on the outside of my house, when I spotted one snail, resting on the left side of the bottom step, that goes to my house. As I looked closely at this snail, I noticed that it had two shells, growing together as one shell. I saw this, with my own two eyes. All my photos came out very bad, so I do not have proof, of what I saw.