You can't add the same tracking number to two items that aren't combined.

OP, I suggest taking photos when you package the items to show both going in the same bag. I guess you could also involve scales (before packed with items displayed, and after). Not sure if it would actually help in a dispute but can't hurt

Put the tracking on the most expensive item.

When you do the refund in paypal, refund with the item that DOESN'T have tracking (the cheapest one), and put a note in the message that this item is in parcel tracking number xxxx.  

I've had to do this many times, no one has tried to claim INR so far.  Most buyers are honest, but def open to scamming.