What sort of things are you thinking of posting that someone else already posts? If you are posting your original thoughts, even if someone else has similar thoughts, the wording is your own, and can be appreciated independently of appreciating other people's posts. For example on this site, I'm sure you know since you have a lot of posts, 30 people might respond supportively to someone's thread, many saying similar things, but I don't think that means the later posts have any less meaning.
Or are you talking about posting a link sharing someone else's idea/work, in which case there is less reason to re-post it after someone else shared it?
What do you mean by you don't like it when the other people post?