First of all i want to propose to give a different name to what was referred to as hanging notes bug type 1: glitch notes. This better
reflects what they are: notes not part of the soundtrack. Type 2 notes are simply notes omitted.

I hooked the midi out from my CT2940 to the midi in from my EMU 1616m 'card', and captured the stream with MIDI-OX until the first
sounding glitch note:

1STATUS DATA1 DATA2 CHAN NOTE EVENT  
299     31    70    10   A3   Note On
399     70    00    10   E8   Note Off 
4
591     28    6F    2    E2   Note On
691     6F    00    2    Eb8  Note Off
7
891     34    72    2    E3   Note On
991     72    00    2    F#8  Note Off
10
1191     2E    72    2    Eb2  Note On
1291     72    00    2    F#8  Note Off
13
1491     28    6F    2    E2   Note On
1591     6F    00    2    Eb8  Note Off
16
1791     28    72    2    E2   Note On
1891     72    00    2    F#8  Note Off
19
2091     28    6C    2    E2   Note On
2191     6C    00    2    C8   Note Off
22
2391     28    6C    2    E2   Note On
2491     6C    6C    2    C8   Note On

The STATUS above is the status byte, and the DATA1 and DATA2 are data bytes. According to the midi specification if the
STATUS byte is the same for the next note it can be omitted. With Note On events the DATA1 corresponds to the note played,
DATA2 to the note velocity. A velocity of 0 is interpreted as a note off. Velocity is an expression type, how fast/hard a key is
pressed down.

As you can see glitch notes occur more often than you can hear, because they are mostly Note Off events. After a legitimate
Note On event, for example an E2 with a velocity of 72 (hex), is followed by a glitch note, with the velocity now send
as DATA1. The velocity is now 0. So it it sent to the sound module like this: 91 28 72 72 00. Sometimes DATA2 also contains
the velocity information of the previous legitimate note, resulting in the dreaded high pitched notes we are familiar with.