Mysterious pipe sticking out the bathroom wall

[minny80]

Hello,
I have this small pipe sticking out my bathroom wall. One of the pipes (the one with the red arrow) is now dripping water (not as regularly as in a leak, just a drop every now and then), which is annoying because it sits just on top of the garden door. I wonder what I can do to stop the pipe dripping, whether I should fill it or just saw it out of the wall. I thought the pipe was kind of supporting sewer pipe above, but as you can see from the second picture, the 2 pipes don't actually touch.
Can anyone shed a light on what the heck are these small pipes for?

Is it not the overflow for your toilet cistern? Check your toilet as the may be an issue with the water level/ballcock

It runs out of the toilet cistern so if the ball cock (fnarr, fnarr) is set wrong, or the valve malfunctions, the excess water doesn't flood your bathroom.

Overflow pipe

Don't block it otherwise the water will overflow inside your house instead, possibly under the floor. Just check the cistern and you'll find there's a problem with it overfilling

You're totally right, it the toilet cistern overflow pipe. Thanks for your help!