No, it can't. The rules about accent marks are very restrictive. Either one or none. Period. By the way, * Ñ is a letter. * Ü is called diéresis and it has a different purpose. read more
The exception to this might be if there were a foreign word (containing two accents) that over time had been adopted into the Spanish language (sort of how the french words clique and cliché have become part of the English language). I can't think of any words that fit that description though. read more
In English, tilde refers to the ~ only (whether used as a accent or not), while accent mark can refer to just about any sort of mark about a letter that affects pronunciation. In Spanish, I am under the impression that tilde has a much broader definition and is similar to our word"accent" in usage. read more