Has anyone else ever wondered...

[DHBirr]

...about the possibility of Doug opening a Gate to leave a world -- and before he can, someone or something coming through from the other side? This crossed my mind while I was looking at an old issue of Phil Foglio's Girl Genius (which I highly recommend to any benighted souls who haven't read it yet; a delightfully crazy steampunk series at www.girlgeniusonline.com).
"What did you do?"
"I ... I was dabbling with transdimensional harmonics."
"In my basement?!!"
"I didn't know it was plugged in!! I opened a portal to the planet Mars!! And through it came a dragon!"
-----
Big Brother is watching you.  And damn, you are so bloody BORING.

[Cobalt Greywalker]

Given that I just got round to reading the thing (yeah, yeah, I know...), my first thought was "Sliders, much?"
OK, my REAL first thought translates to , but that was my immediate next thought!
ANYway, from what I recall from DW2 & 5 it goes like this:
1) Doug plays Gate Song
2) Gate Opens to void.
3) Doug enters gate (probably muttering in the back of his mind comparisons to the Abyss, and good intentions, and so on and so forth[1]...)
4) Gate Closes.
5) "Time" passes.[2]
6) Gate Opens to (brave?) new world.
7) Doug exits Gate (with about as much control as [3], i.e. None whatsoever).
8) Gate Closes.
So, No. Not unless Doug Opening a Gate attracts a Gate coming the other way somehow...
[1] As an aside, can anybody think of a song about good intentions? I can just see Doug playing it in DW5 and gating a nice trip to where good intentions lead...
[2] Can time pass outside Space-Time? Or do we have to deal with a 2nd time dimention like I read about about about 5 years ago?
[3] Put this way 'cause quite frankly, there are SOOO many comparisons I could make...