possible close encounter on military training ground in the 90s in Germany

I grew up in Drove, Germany (originally born in Long Beach,CA).  Very close to Drove was the so called "Drover Heide," which is a large open area with a lot of heather and little birch tree groups.
It used to be a military training ground for about 200 years and it was strictly forbidden to enter it ( it was also very dangerous because of old ammunition that was everywhere).
At the other end of the Drover Heide was an American military base with the type "Nike" defense missiles.
As kids we used to play on the drover heide and in the woods around it and when the military activity got less in the early '90's, I started to go searching on the drover heide first just for old musket lead balls, but later, I also started taking artillery and mortar grenades home (I used a cheap metal detector).  I then disarmed them and later blew the explosives up at night in the forest with some friends (just for fun and bragging rights).
I know now that this was extremely dangerous and also illegal, but when I was 16, it was my hobby and important to me.
One day I was searching at a dangerous spot again and heard a strange noise.  I could not tell exactly what it was and where it came from.  When I looked around I couldn't see anything.
I thought it was possibly a vehicle from the military police so I got a little nervous.  It didn't really sound like a car however so I kept on searching.
About 5 minutes later, two young men (maybe 20-25 years old) where standing about 10 meters away from me.  They where identical twins with short brown hair and also identical clothing (dark grey-black color).  Their clothing looked more like some type of uniform/ jogging suit.  They where about as tall as I was back then (6 feet).
They both smiled at me and one asked me what I was doing.  I didn't want to tell them the truth so I told them that I was just looking for old musket bullets.  Then they smiled and walked away.
Maybe I am just overreacting or paranoid, but I don't think that these 2 young men where normal humans.  I have never seen them afterwards again.
Meeting anybody back then on the Drover Heide was very very rare because everybody was afraid of the military police.
Witness indicates that the date of the sighting is approximate.  PD