Sourcecode combinatorics Objective:


  The task is to create two programs using the same or different
  programming languages. The sourcecodes will be combined in two
  different ways and the resulting sourcecodes can be in any programming
  languages. The four programs (original two + the two combinations)
  should output different things.


Rules:


Your programs (all four) should not take any input (from user, filename, network or anything).
The first program should output exactly Hello, nothing else.
The second program should output exactly world, nothing else.
The first combinated program should output Hello human!, nothing else.
The second combinated program should output Hello computer!, nothing else.


Here is how the two combinated programs may be created:

First combined program:


Choose two numbers (equal or different) between 1 and 6 (that is: 2, 3, 4 or 5), the two numbers are called: n1 and n2. 
Copy n1 number of characters from the first program and paste into the combined sourcecode
Copy n1 number of characters from the second program and paste into the combined sourcecode
Copy n2 number of characters from the first program and paste into the combined sourcecode
Copy n2 number of characters from the second program and paste into the combined sourcecode
Next, start over copy n1 number of characters again and so on. Copy from start to end from the sourcecodes, paste from start to end into the combined sourcecode.


Second combined program:


The sourcecode is the reverse of the first combined program sourcecode above. You may replace up to 3 characters at any place afterwards (optional). You can replace the up to 3 characters with any other characters. Replacing means 1 char for 1 char at up to 3 different positions on the sourcecode. The final sourcecode size in characters should therefor be exactly the same size as the first combined program size. 


Example creating the combinated programs using numbers 3 and 4:

            First program:    {'Hello'}:p
           Second program:    /*         */ console.log ("World");
 First combinated program:    {'H/* ello    '}:   */ console.log ("World");
Second combinated program:    ;)"dlroW"( gol.elosnoc /*   :}'    olle */H'}


Be sure to declare all four programming languages that you use (even if they are all the same) and what numbers you have used when creating the first combinated sourcecode.

This is code-golf, shortest code in bytes for the two sourcecodes wins! Good luck, have fun!
Befunge-93 x4; n1=5, n2=5; 100 75 chars
I put the 4 programs into 1 file for debugging:  (it outputs a random one of the four programs)
 vv  |2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|23
&gt;??#@&quot;oll&quot;&quot;eH&quot;   &gt;:#0#,_ @    #
     |2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|23
&gt;? #@&quot;dlr&quot;&quot;ow&quot;        &gt;:#0#,_ @0&quot;!namuh olleH&quot;&gt;:#,_@#:&gt;&quot;Hello computer!&quot;
     |2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|23
 &gt; #@&quot;oll&quot;&quot;dlr&quot;&quot;eH&quot; &quot;ow&quot;   &gt;:#     0#,_   &gt;:#@    0#,_ #@0&quot;!namuh olleH&quot;&gt;:#,_@#:&gt;&quot;Hello computer!&quot;
     |2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|2345|23
  &gt;#@&quot;!retupmoc olleH&quot;&gt;:#,_@#:&gt;&quot;Hello human!&quot;0@# _,#0    @#:&gt;   _,#0     #:&gt;   &quot;wo&quot; &quot;He&quot;&quot;rld&quot;&quot;llo&quot;

The separate programs are: (one per line)
&quot;oll&quot;&quot;eH&quot;   &gt;:#0#,_ @    #
&quot;dlr&quot;&quot;ow&quot;        &gt;:#0#,_ @0&quot;!namuh olleH&quot;&gt;:#,_@#:&gt;&quot;Hello computer!&quot;
&quot;oll&quot;&quot;dlr&quot;&quot;eH&quot; &quot;ow&quot;   &gt;:#     0#,_   &gt;:#@    0#,_ #@0&quot;!namuh olleH&quot;&gt;:#,_@#:&gt;&quot;Hello computer!&quot;
&quot;!retupmoc olleH&quot;&gt;:#,_@#:&gt;&quot;Hello human!&quot;0@# _,#0    @#:&gt;   _,#0     #:&gt;   &quot;wo&quot; &quot;He&quot;&quot;rld&quot;&quot;llo&quot;

Edit:  This time, I took advantage of the replacement rule and replaced two characters in the second combination.