You have a valid question about authencity of version.
But just use of little common sense could clear the cloud of doubts..
Think by yourself if what that Gentleman on INS VIKRANT told you ppl was correct version...Are our Indian Defense officials so fool who would dispatch full fledged fleet having 19 Quality officers and 178 Sailors for suicidal attempt?? Hence ,very clearly Torpedo was targeted on INS KHURKI only!
This is well known fact that about 200 Valuable life were lost with that sinking! Then think by yourself and decide...
And yes,next time if you are lucky enough to meet same official on INS VIKRANT, kindly ask him not to spread such rumours and keep information polished with little work on history books with related incident.