Relisting the same old property

Here's a question for the realtors out there:

Is it legal to pull a house and relist it immediately? Is there a waiting period required?

Here's an example. This triplex in the SE was just re-listed as MLS #8007641. It has been on the market for over a year listed as #6019453, and obviously didn't sell.

I've seen this happen with a number of the properties I have looked at, and besides being dishonest, I just wonder if it's also illegal.

Anyone care to comment?