Dual agent for pocket listing good/bad?

[Keaton Smith]

I am currently in the due diligence period for a duplex that a realtor I work with has been working on getting to sell for a while. I was able to offer a deal that the seller is comfortable with and we have been moving along fairly well. However, due to my ignorance, I am now finding out that the realtor I am working with is also representing the seller as a dual agent.

Is this a common practice in REI to have dual agents in pocket listings? My understanding was that having an agent represent both parties was generally to be avoided.

Thanks for your input!