Symptoms
K2 seems not integrated with Sharepoint, is requesting login again.
Diagnoses
The issue here is to do with logging into Sharepoint when wanting to use the K2 app. You get multiple log in attempts and would like to know what is the best possible way to get around this.
Resolution
This is expected behaviour as one login is windows authentication and the second is for K2 Oauth authentication, so you will need to do this only on the first time you login to sharepoint.