Should a 2LT salute a 1LT?

The answer is no unless the 1LT is the commander. I know the regs and all, however, there are traditions and the tradition is that an LT is an LT.

"If you can't move it, paint it. If it has a switchblade knife, salute it" (-Tom T. Hall- Salute to a Switchblade Knife)

The 1lt is senior to the 2lt. It’s just that simple, and so of course the 2lt should salute. To not do so diminishes good order and discipline and erodes proper military bearing.

Salutes should be given as regs and protocol demand. Saluting seniors never bothered me, even when I was a seaman and had to salute everything that moved...or so it seemed. I laugh now because years later after being commissioned as a Chief Warrant Officer, I came to realize that I was returning way more salutes than I ever had to make when enlisted. I've always considered the salute to be an acknowledgement of respect of the senior-subordinate relationship between ranks. That doesn't mean that I always respected the dipstick that I saluted, but I certainly respected his/her position. Yes, 2nd LTs should salute 1st LTs.

Kind of like a Lieutenant Colonel does not have to salute (or obey commands) from a Colonel? I mean he is almost a Colonel right?
WTFO?? Yeah, I was not an officer so I don't get it. Huh. What is this the snowflake ARMY??

This issue has been around forever. It was not new when I was a butter bar in the early 60's and will be around long after I am dead. The practical reality is when you sign on with any organization you buy into their culture and rules or you will not do well. I don't care if it is the military or humble food service. If a server in my restaurant does not show up clean neat and properly dressed or does not render proper customer service they are gone. Same for almost any other job. Quit whining, bloom where you are planted and do your job. If you have a problem saluting it is YOUR personal problem and you need to get your head right

Yes. No question about it in the Marine Corps.

Should a Lieutenant Colonel salute a Colonel?

When I was commissioned, I returned to OCS as an instructor a few months later. I saluted the 1LT that had been my Platoon TAC. He told me quietly in private that it wasn't necessary. Something about "no honor among thieves".......
So I never did it again.

Salute the rank. Salute the position. As NCO we enforce and practise regs and traditions.