mdt24 and mdt34 table snippets reuse tab stops, so column 3 and 4 cells are mirrored #7

The 2x4 and 3x4 table snippets (mdt24, mdt34) reuse the same tab-stop number for two different columns, so the two cells are mirrored: typing into one changes the other.

Repro (Sublime Text 4215, MarkdownAssistant 1.0.3 from Package Control)

1. In a Markdown file, type mdt24 and press Tab. The snippet inserts:

   | 1,1        | 1,2           | 1,3  | 1,3  |
   | ------------- |:-------------:| -------| -----:|
   |  2,1      |2,2 | 2,3 | 2,3 |
   

2. Press Tab twice to reach the third cell and type X.

Result: both the third and the fourth cell of that row become X (two cursors are active on that field):

| 1,1        | 1,2           | X  | X  |

I only typed into the first row. From the snippet source the data row repeats ${6} the same way, and mdt34 repeats ${3}, ${6} and ${9}. The 1x4 table (mdt14) works correctly for comparison: typing X in its third cell leaves the fourth as 1,4.

Cause

In Tables/t24.sublime-snippet the fourth column of the header uses ${3:1,3} again (it should be ${4:1,4}), and the fourth column of the data row uses ${6:2,3} again. Tables/t34.sublime-snippet has the same duplicates (${3}, ${6}, ${9}). Sublime treats repeated numbers as mirrored fields, so the fourth column can't be edited on its own and the tab stops don't go through all the cells.