Yes Toddy, I know its not the same and won't give the authentic truffle taste. Absolutely.
I just mentioned what I had found on Google that some people use dried porchini as a substitute.
Tengu did ask if there were any known substitutes, and I just answered that part of the question.
It will definitely not taste exactly like truffle, as there is nothing else that does, which is why synthetic flavouring was developed years ago, and makes the "flavour" accessible to those who cannot afford the real thing. So, one could also use this synthetic flavouring as a substitute.
Nothing realy substitutes the real thing, as I said before.