Infrared Spectroscopy Puzzle

[GammaGirl]

 When obtaining an IR spectrum, a secondary amine should exhibit only one N-H stretch, however, when a student ran his sample, two N-H stretches appeared in the spectrum. What could account for this? 

[exchemist]

 When obtaining an IR spectrum, a secondary amine should exhibit only one N-H stretch, however, when a student ran his sample, two N-H stretches appeared in the spectrum. What could account for this? 

This sounds like a problem you have been set. We don't do people's homework for them. 

 

But if you put forward the answer you would propose, we can discuss it, certainly.