Lightstreamer Server allows multiple Adapter Pairs (i.e. Metadata Adapter + Data Adapter) to be installed, by putting multiple directories under its "adapters" directory,
each one with its own adapters.xml configuration file.
However, a single client session can access to only one Adapter Pair.

With the forthcoming 3.5 Server release, the Adapter Pairs will be generalized to Adapter Sets. Hence, in a single adapters.xml, it will be possible to configure multiple Data Adapters (but still a single Metadata Adapter) and a single client session will be able to get data from all of them.

In all cases, each configured Data (or Metadata) Adapter can be either local or remote.

By default, a different process is needed to run each Remote Adapter. However, you can create your own hosting program and play multiple Remote Data Adapters by it, through the provided Lightstreamer.DotNet.Server.DataProviderServer API class.
See chapter 1.6 in the included "DotNet Adapters.pdf" for an introduction.