Are different hash algorithms ever used together?
For example, Is possible to combine (Concatenate or Chain or XOR) Skein SHA-3 candidate with Grostl SHA-3 candidate to increase security?
Note: I just want more secure output and CPU cycles does not matter. I would like to come up with my two combine hash functions to protect a certain document's data integrity that I have. And of course, I want this protection to last for the next few years, So I decided to choose to combine two of SHA-3 candidates, Any suggestions?