In HL2, when you take the first teleporter, you can clearly see Lamarr jump in and get teleported to a beach.
Later in the game, when you take the teleporter Mossman was working on(when you arrive at Kleiners lab, and tell you it’s been a week), Lamarr is there!
How?
Kleiner either found her or she found her way back. There’s no way to know how far the beach was from City 17.
Ask VALVe
legit question that cannot be answered for real dog
maybe she jumped on one of the crows and it was her mount to arrive to city 17…
Or maybe just as you she was also being teleported to different places all the time (you got teleported to a beach, to the water, to breen, Eli’s lab, kleiner’s lab and finally the street), maybe she teleported on Kleiners back some minutes after you left over the canals.
I’ll probably e-mail them, just for the heck of it.
EDIT: there. email’d Gabe.
Aren’t headcrabs, like, prominent in City 17 and can’t debeaking, like, be repeated on another headcrab?
STOP SAYING LIKE > 
But yeah, that is one weird happening. I would never have picked that up if you hadn’t mentioned it.
Lamarr isn’t constrained by the bounds of normal physics.
There’s only one Hedy! >
Gordon then teleports away, Lamarr being too far away to teleport with him, but like Gordon she may have been caught in a temperal displacement and went to several other places before returning to Kleiner’s lab.
from hl wikia
…and maybe Kleiner, like, named the headcrab after his previous pet.
And maybe you, like, NEED TO STOP SAYING LIKE SO MUCH JESUS CHRIST
Lamarr kills other headcrabs
Just what I said before but in other words…
And maybe you should stop being so overagressive over a joke.
Lamarr could have ended up back at Kleiner’s lab at the same time as Gordon. She (do Headcrabs have genders?) left Gordon to jump on a crow, but neither of them were actually on a teleportation pad when Gordon teleported away. It’s possible that Lamarr had a displacement field around her just like Gordon did, and ended up repeatedly going to the same places as Gordon. When she jumps on the crow, though, she doesn’t have the effect around her that Alyx had and (I assume) Gordon would have had, so I have no fucking clue.
Maybe 2 streets over from Kleiner’s lab there was a beach. Or something. Where you somehow couldn’t see the city.
Or that you just saw the other way.
the last place Gordon teleported to wasn’t that far away from the teleport, in fact it was right next to Dr. Kleiner. It’s pretty safe to assume that when all of the teleporting died down Lamar ended up pretty near by as well.
Edit: it seems BahamutBBob beat me to it.
Lamar will be sitting on Klieners shoulder in Episode 3, after being shot into space inside a rocket.
It would be awesome if the Half-Life series started to have a running gag where Lamar keeps getting teleported/shot/various transportation into far off places just to return the next game without any explanation.