Hi,
Can we have more than 1 VM on the same AMI ?
With each VM running different application
Multiple VM on a same AMI
You might be able to do this with something like virtualbox - but then you lose high end GPU support in the VM. If you don't need GPU support, it might be easier to use a smaller CPU instance for each host, rather than trying to split a larger instance into multiple ones. Behind the scenes, AWS is basically doing this for you - the smaller instances are basically Xen VMs that are partitioned form the larger instance types.