"listed and sold simultaneously"

I see this every now and then on comps. What exactly is the purpose of listing and selling a property simultaneously?

many realtors have clients looking for a specific deal and when they can steer a client inot a deal without evne having to list it, they’ll list it anyway so they can to establish comps.

Same thing happens with a short sale. Lender approving short sale wants to see that property is listed for sale.

Not sure if this is the right place for this but it reminded me of this.

I was selling my house years ago and listed with a realtor that said could sell my house in two weeks. Three months later I told her I wanted to discontinue and sell it myself. She said leave her sign up and put my FSBO sign up at the same time. I have never seen this on anybody lawn before and I didn’t go for it and actually I sold in two later myself but have you ever heard of that a realtor and FSBO at the same time?