Ok to list for sale at TDNAM and Sedo?

[NTWWeb]

I saw a domain listed for sale at both TDNAM and Sedo.

Does it mean that if buyer purchases at one, you just need to ax the other listing?

Is this common, recommended and/or ok within the domain community?

Is there a penalty for this? $$s
or some 'yur a bad, bad boy' lecture? :D

[welkin]

I think, it depends on how the domain is listed.
If it's not an auction and just listed for getting some offers I don't see a problem. You can list it at 10 places as long as you accept only one offer.

[NTWWeb]

Thanks, no issues if honor is maintained then.