My personal opinion is that if you don't set ground rules for both dogs, you will have a fight… each needs to respect the other and since Shango was there first, he should be greeted first... and Mowgli needs to learn to wait his turn.
But first you will need to teach Mowgli some basic Obedience, like sit, down, stay.... You need to greet Shango first and have Mowgli wait.... if he buts in you need to put him back in a sit/stay until you are done with Shango and release Mowgli
