Hello Chandra Shekhar,
I understand that you are unable to use two submit connections simultaneously. This happens if you configure the submit action at the button properties. As a solution, set both button properties' action to Rules and Custom Code (right click Button > Button Properties and then select the action).

After setting this up, proceed to your Home tab, select the button, at the ribbon click Add Rule > When his Button is Clicked > Submit Data - a window will prompt you select which data connection to associate with the button selected.

Repeat steps for the other button. Hope this helps.