You can come back on new visa but when you go to stamp ur residence they the immigration will ask for NOC from the previous sponsor cos ur old visa is still valid you hve to cancel the visa.....or take NOC from previous sponsor....when they stamp ur new visa your visa number will never change you will get the same number,it is a net work all ur document is in their system.....the visa what you hve is a entry visa......after you do your medical finger print and when it goes to immigration it will be held up....or you hve to pay fine.......good luck.