Using 2 midi keyboard at once

hey guys, i am sorry if this is posted at wrong section, i couldn't find the right place to post it and this was the only reasonable section i could find for this topic.

Similar to CoreAudio, the term refers to the built-in MIDI support embedded in Apple's OS X.

An addition to the original MIDI specification that allows for consistent playback on any instrument that is GM compatible. Achieved by requiring that groups of sounds have very specific locations (a piano sound on one synthesizer will have the same location on another,) that all instruments have 24-voice polyphony, and that certain continuous controllers are similarly defined.

Musical Instrument Digital Interface.

Synchronization systems available to MIDI users that include MIDI Clock and MIDI Time Code.

A MIDI connector found on electronic synthesizers, that passes through untouched the MIDI data that is received by the MIDI input.

A form of time code that is based around real time. Like SMPTE time code, the units of measure are hours, minutes, seconds, frames and subframes, but sent as part of the MIDI stream.
(See SMPTE Time Code)

A term coined by MOTU to denote a method of coding MIDI data to allow the computer to re-trigger this information with grater accuracy. Before time stamping, MIDI transmission suffered from a certain amount of "slop" due to a sequencer program having to rely on the host computer's clock to manage timing issue.

A standardized file format for exchanging MIDI data independent of originating software or platform. Comes in two flavors. Type 0, which is a single track that contains all sixteen MIDI channels and pertinent information. It should be noted that although the information is presented in a single track, the individual channel information is kept discreet and can be easily extracted.

Hi.

I see a lot of drum MIDI loops collections, like this:
http://www.toontrack.com/products.asp?item=63

And of course there are lots of audio (AIFF/WAV) loops CDs.

But are there any any piano / organ / clavinet MIDI loop collections out on the market?

thanks in advance!