In practical terms, yes. Most students with one disability have multiple disabilities. For example it is conceivable that you have many of the symptoms from the list of Asperger's Syndrome (no one has them all) and also have a two-year gap in a subject area that would qualify as an LD situation.
In technical terms, no. Even give the above situation, which more closely reflects reality, for simplicity in dealing with singular diagnoses, the DSM-IV and other standards often exclude those with one diagnosis from other diagnoses. This is particularly true with being labeled as LD. There are also some exclusions in the AS diagnosis.
All these labels are just convenient approximations of reality. We have a lot to learn about how many different types of autism there are. We are not even beginning to understand the exact combinations of genetic switches that cause one form of disability such as HFA verses a very similar combination that cause another form such as AS or ADD or ADHD. These four conditions have similar symptoms and seem to be closely related, but are also somewhat distinct. This implies that there are some genes in common and some genes that are different. When that genetic mapping is complete and diagnosed based on DNA, all that will become more clear, and we will no longer diagnose based on a shopping list of symptoms like in the DSM. Until then, technically you can only have one of these labels and it may not reflect other genetic switches that are also turned on or off in an atypical manner, resulting in a very unique and individualized combination causing and unknown disability.