As long as you don’t run
meteor update from the project root of those existing projects, you can start a new project and update that to the newest version of Meteor:
meteor create <yourProjectName>
The newest version of meteor will be downloaded, your new app will be updated to use the newest version of Meteor, but the old projects running on 22.214.171.124 will continue to run just fine. (There will still be a copy of 126.96.36.199 and all relevant packages on your dev machine that the meteor tool will use for builds of the older projects.)
After this, future projects you create will use the newest version of Meteor.
Even if you do accidentally
meteor update one of the old projects, you can always run
meteor update --release 188.8.131.52
although I don’t think that always works seamlessly (I’ve sometimes had to modify the
.meteor/versions files manually to fully restore the previous state).