Two Oval Holes in Sink Drain Pipe

In our bathroom sinks, when I took the stopper out, I noticed two oval holes near the top of the drain pipe (one on either side). The holes are above the thread area for the stopper. Does anyone know what these holes are and what they are there for? Do they drain down into the drain pipe (similar to an overflow)? I have attached a photo of the oval holes. In the photo they are whitish color as they seem to have soap scum

Its very hard to see your pic..probably my computerpicture is to close,is this something new or are you just noticing it

I tried lightening the picture up a bit.
Sure looks like the overflow holes to me.
Does your sink have a small overflow hole built into it?

it is the over flow drain

Thank you! Yes the sink has a single overflow hole in the basin itself which is what threw me off. I wasn't sure why the basin would have an overflow and then the drain itself would have another overflow. But I have read it is possible to have both.

The slotted holes in the drain are the exit points for any water that enters the bowl overflow hole.
From there the overflow water can run down into the tailpiece.