There are a couple of ways to do this.
I would just drag one MIDI track onto the other one
and then use the glue tool to ‘blend/merge’
them into one track.
For more precise note placement.
1-Open one track
2-put the cursor on the 1st event in the track (you might have to turn ‘Snap Off’)
and then use ‘select all’
3-Now use the ‘cut’ function (command X on mac)
and the parts get moved unto the clipboard
Don’t move the cursor
4-Close the track and then open the 2nd track and use the
If the original separate tracks are on different MIDI channels, set the MIDI channel of the new blended track to ‘Any’.
If you do this remember what ever sound source you are using to hear the sounds (VSTi or external hardware device) has to be able to respond to multiple MIDI channels.
Or you could use the Logical Editor to make all events on the new track one MIDI channel.