If that was your intent, that isn’t want l what you implemented. In both cases you set a timer for 2 minutes in the original code which is what I used as a guide.
You can do the same with Expire based timers. You would have a second timer Item and then use the name of the timer Item to send the right alert in the timer rule. Pretty much as you have.
I recommend using Design Pattern: Human Readable Names in Messages.
The Associated Item DP requires the items to bed named do you can easily created the name of an associated Item for there name of another one. You don’t have to change the name of your other contact items but you need to be consistent in how you name the timer items. Above I appended “_Timer”.
Like I said on the outset, you are trading additional items in exchange for reduced complexity in Rules. But because items are relatively simple it is more than a fair trade. If it is a code between a two new items per window versus two timers, a lambda, and a Map, the choice is simple. If add 30 or 40 new items to avoid that complexity in rules.
But to answer your question, you can only use one timer Item if the amount if time remains the same for both uses.