Obviously you have installed Murchison 2 as a "stand alone". Even if you installed Murchison 2 into your TS2010 directory, the Murchison 2 installation will not have deleted your old TS2010 Trainz .exe command that starts TS2010 (or the TS2010 icon on your desktop). You must be clicking on the wrong .exe command (or icon) to start TS2010. By the sounds of it, you are clicking on the Murchison 2 icon, rather than the TS2010 icon. (or manually clicking on the Murchison 2 .exe rather than the TS2010 .exe).
When you are clicking on the Murchison 2 icon, obviously only Murchison 2 is starting. Even if Murchison 2 is installed into the TS2010 directory, if you click on the ("stand alone" Murchison 2 icon) only Murchison 2 will load.
You should still have your old TS2010 icon on your desktop, and if you click on that, it should start TS2010. If the TS2010 icon is no longer on your desktop, manually go into your TS2010 directory and double left click on the Trainz.exe file that I explained in my first post.
I'm confused as to where Murchison 2 is installed on your computer. Is it inside your TS2010 directory or have you installed it into it's own separate directory (separate from the TS2010 directory)?
Check inside your TS2010 directory to see if there is a sub directory called Murchison 2.
Regardless of where you installed it, all you need to do is copy a file called Murchison 2.ja (1,153,801KB) that you will find in a sub folder in the Murchison 2 directory called Builtin. Copy that file into the Builtin sub folder in the TS2010 directory.
Now open CMP 3.3 and in the top left hand corner, click on File and then go down and click on Extended Database Repair.
Depending on how much extra content you have installed, it might take a while for the database repair to complete. Don't interrupt the repair. All of Murchison 2 is in that .ja file. By doing the database repair, M2 (& the 29 sessions) is actually being installed into TS2010.
Now all you have to do is find the right icon (or .exe) to start TS2010. Once started, go into Options. Then in the General screen enter your Murchison 2 add-on serial number, then click Add. Then go back to the main menu and click on Start. Then check that the Murchison 2 route (& the 29 sessions) is showing up in Routes and if so, exit TS2010. Find the Murchison 2 directory, no matter where you installed it and completely delete that "stand alone" Murchison 2 directory and the Murchison 2 icon on your desktop. (that assuming you no longer want Murchison 2 installed as a stand alone). Murchison 2 doesn't have it's own desktop icon if it is installed in TS2010. (only needs a icon if you want it installed as a "stand alone")...
Cheers, Mac...