The concept of being in two places at the same time is a fascinating one, especially when it comes to standing with one foot in each of two adjacent countries. Think about these countries that are adjacent of each other and you could exercise this theory in:
Of course, that's even better: at the border triangle between the Netherlands, Belgium and Germany, if you have big feet, you can be the same in three places.
I lived almost on the Belgium-Netherlands border until I was 23, when I walked down the street and came to the intersection, I had one leg in Putte-Stabroek (B) and the other leg in Putte (NL); I had to cross the border anyway to go from Belgium to another street in Belgium because the street that connected the 2 streets was Dutch territory.
It is also possible in Kenya-Tanzania. In fact, that's what I did, in 2017, under the strict supervision of a group of giraffes. By the way, did you know that Kenyans are vaccinated against smallpox in their right arm, and Tanzanians on the left? They do this to prevent illegal crossings.
The Netherlands and Germany too. For example in Kerkrade. If we had three feet, it could even be done in 3 countries at the same time, at the Tri-border Point in Vaals.
In Baarle-Hertog/Baarle-Nassau, you can even go through the entire village by alternating between Belgium and the Netherlands. Some buildings are right on the border there. For example, when you enter the Zeeman, you walk across the border all the time. They took the front door there as deciding in which country the building is located. !