Angelika,since the idea of twinsouls is bogus now to me,or more to the point,NOT what people think they are,then I will respond from the soulmate point of view.
People are very confused what a soulmate is. A soulmate is someone we chose to incarnate on this plane again with for purposes of learning. We have many soulmates,of different "intensities". We dont always stay connected with them on earth,they may be in our lives for many years or just temporarily.There are cases such as a sun/moon conjunction in a synastry,where you may be in and out of each others lives your whole life,..this is the intense trait of that aspect,but once again, depending on the rest of the synastry.There is always some form of GROWTH with a soulmate. They are not always of happy circumstances,but if we stand back and take a mature look at things,we should be grateful for what was learned!! Sometimes we need to go very much "within" to understand what was meant to be learned.

Ive done a few soulmated/karmic charts which didnt have pluto/venus aspects,but had tons of others such as a lot of Saturn,nodal,and angular aspects on the personal planets.
A person will,or should know if someone is a soulmate by looking at the persons face/eyes. Maybe Ive just been blessed with how to see this,I dont know. When you either
1) look at someone and see a certain famililarity,or what you MAY think is love at first site
etc,then take a look at the synastry..you shouldnt be surprised!
2) if when you first meet someone,and you already feel "at home" with them, same idea!Look at the charts.
3) oops,I thought I better edit this to say there may be times you feel an intense dislike for someone,again,look at the charts(if you can get the birth data out of that person,hehe)
Anyway, these are some on my own thoughts and opinions on soulmates based on my own experiences and studying the concept and talking with others. 
[This message has been edited by Aries (edited 02-10-2001).]