Let say I recorded many phrases in a pattern (each phrase can be played by pushing one of the 15 keys A-B-C, etc....)
Since the pattern already has a tempo saved along with it, how
can I synchronize the playing of these phrases from a second MIDI keyboard to ensure both play at the same tempo and start at the same time ?

You can synchronize them via MIDI clock. You make one of the units the Master clock, and the other the Slave.

On the MO the clock can be found:
Press [UTILITY]
Press [F5] MIDI
Press [SF3] SYNC
MIDI SYNC when set to “MIDI” will make the MO the slave to the external unit. It will receive tempo set in the external device.
You must also set the SEQ CTRL (Sequencer Control) = IN so that when you start the external device, the MO will also start. And it will Stop when you stop the external unit.

If you want the MO as the master clock:
MIDI SYNC = “internal”
CLOCK OUT = ON
SEQ CTRL = OUT

Ok but if i want start play the MO sequencer and in the same moment start the cubase seq. how can i do? this is for export track by track what i recorded in the Mo

The setting for the MO are the same as below.

On the MO the clock can be found:
Press [UTILITY]
Press [F5] MIDI
Press [SF3] SYNC
MIDI SYNC when set to “MIDI” will make the MO the slave to the external unit. It will receive tempo set in the external device.
You must also set the SEQ CTRL (Sequencer Control) = IN so that when you start the external device, the MO will also start. And it will Stop when you stop the external unit.

You will want to go to the Cubase Project synchronization setup in the Transport pull down menu and under MIDI clock destinations check MO6 Port 1 .  This will send MIDI clock to the MO from Cubase.

It’s works! thank you very much..
Now i have to understand how Studio Manager works…