One-Upsmanship

Your coworkers aren't listening to you. When you share how your weekend was, or what plans you're making for vacation. They are only thinking about their amazing reply. While you tell your story, they are already putting together their response; a better story than yours, or a crazier weekend, or the amazing vacations they've been on.

One-upsmanship is different than a sympathetic response. Some of the guys I work with think they are great story tellers, so no matter what subject you bring up, they have a better, wilder, funnier, more shocking version of their own to share. I'm not sure if this is just a guy thing or not. I'm leaning toward the machismo rationale on this: "machismo is strongly and consistently associated with dominance, aggression, grandstanding, and an inability to nurture." (Wikipedia)
Yes. 'Grandstanding' is another synonym that can be plugged in here as well. Once we begin to peel back some of these behaviors we can rest assured that the meeting of minds rarely happens and 'true listening' is a lost art-skill.

I'm sure I've done it, and I will most definitely be a repeat offender. But with some practice and self awareness, I can focus on what someone is really saying and engage in conversation, not me-versus-you story telling.