This isn't specifically about sharePoint although the Infopath form is used in a SharePoint library, but there are probably more people participating here that know Infopath than there is in the Infopath section as I get no hits there.
I have a form in Infopath with a main section and two different sections with signatures enabled. Employee signature, and Supervisor Approval. Both signatures are set to sign the main section. When someone clicks on the Employee section signature control and launches the signature dialog and fills it out, it fills out both signatures with the same person.
We want two different people to be able to sign it individually but we want the approval signature to sign the preceding signature. So there is something wrong with the way I have my sections or signatures set up.
I have the signature type set to "each signature signs the preceding signature" for the Supervisor Approval section. I wanted to set the employees section to allow only one signature. When i set it to that, it changes the properties of the Approval signature as well to the same as the employee signature. Maybe that's what i want, or maybe I want both to have that other choice of "each signature gets signed individually". But that should give you an idea of how these signatures think they relate to each other in a way that i would not like them to.