Ignoring similar columns when concating matrixes vertically
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In matlab I have a 128 by n matrix, which we can call 

>    [A B C]

where each letter is an 128 by 1 matrix.

So what I want to do is concat the above matrix with another matrix,

> [A~ D E].

Where A~ is similar in its values to A. 
 What I want to get as the result of the concat would be:

> [A B C D E],

 where A~ is omitted. 

What is the best way to do this? 