My dilemma came after I got a call for an interview from company 'B'
Personally I feel that it is ethically not correct, or unprofessional to get an interview at the other company.
So what do you suggest in this regard?
There'sFor me, there's no dilemma here.
Either you value your word, your reputation, and your personal ethics, or you don't.
I suggest that you think about which is more important to you - the potential of the job at company B or your reputation, and then act accordingly.
Once I accept a new job, I'm all in. I don't look back and inform other parties that I'm no longer interested. My personal reputation is worth a lot to me. Your mileage may vary.