Which way is the best?

I'm not really sure. I think we should talk kindly to all people if at all possible. That would be the best.

I don't understand why we can't be nice and sweet to everybody. One can choose not to be two-faced.

tkonlinevn, Stark resemblances does not signify anything - it is our attitude and perception towards the other party that suggest your karmic bond with the person. Our feelings are likely generated because of our irrevocable actions in the past that are generally beyond our scope of control. And because we can't turn back time to alter our regretful past, our present and future remained in status quo based on our earlier decision via freewill. Albeit the law of causality might be rigid, but our minds and heart isn't. Hence, phenomenon of resemblance resulted in an implicit behavior or mindset that served under the theory of 'Time Machine'. Because in the realm where 'Love is blind', similarity will naturally (and usually automatically) perceived from the source where it first began and the seeming linkage is establish, although it pretty much illusional. I will illustrate a simple example: There are times when we felt that we made mistakes and regret in life, with regards to our relationships. Equally often, it might not be mistakes - perhaps we felt that we could 'do more' (whatever 'more' meant to us philosophically). And because the manifestation has already occur and we are unable to undo our circumstances, we shoulder certain unconscious anguish or bitterness that carry in our soul. Such suppression are dormant and only brought into surface when the concept of time triggers an astrological or karmic pattern to bring forth such situation once again. Then you might question - why such a phenomenon? There are two likely reasons: I) It served to test the foundation of your relationship. Those who are stuck in the misery of their past will often create the path of destruction for their relationship of the future. II) The absence of graduation or higher learning with prior lessons resulted in reiteration of the same chapter once again. What we cannot master, we learn again. I suggest instead of first leading yourself into the direction of asking 'Should I' - I reckon you should reframe your question and direct the question inwardly. 'What does this mean to me and development?' You might want to understand if there's action(s) you wish to compensate for your relationship(s) or encounter(s) and unconsciously directing your effort(s) towards this 'proxy'? Resulting in the identity of your relationship being questioned here as well. Only with careful examination of yourself, would you be able to have the clarity to decide your course of action with wisdom.

Yes there are some people like this and it is odd behavior. I am one and the same no matter who I speak to, so odd that they have this type of reverse type behavior and maybe it has to do with some hidden ill feelings towards the person they switch their behavior with.

I talk to everyone in the same way. Unless that person gets on my nerves, then it's a different story all together. If people are nice to us, then we too should be nice to them.

There's no best way. You don't act like that because you wanted to but beause it is your nature. You are born like that. You don't choose to act differently between your parents and others.