Has anybody seen this before?

I had 33 BTC in my wallet and I sent 8 BTC with Multibit. The client shows the current balance of 25 BTC, which is correct. However, The Blockchain shows that I only have 20 BTC in my final balance! And it shows that I sent 8 BTC to one address and almost 5 BTC to another address in the same transaction. How is that possible?

What can it be? Anyone?

Thanks