First, you cannot double the speed of 55Mbts to 100. The laws of physics wont allow it!
I think what they are saying is, that all the quoted speeds can be used simultaneously.
So for example, if you had an internet connection at 55Mbts and (at the same time) you were transferring a data file from one machine to another, each speed could be used together. One for the internet and the other for data transfer, but the sources of each would be different.