Data transfer over a LAN

I am having a small LAN with 10 comps. with win98 as OS.
Onece a problem arrived was, there were two persons working on negibhourig comp to each other say on comp5 and comp6. Both were working with microsoft wordpad. Now problem was that when one person copies some data in clipboard , other if pastes someting in his document , the data of other person gets pasted. and vice versa.
i.e. if first persons copies someting in clipboard and after that other person also copies the data, and when first person pests its data, data of othere person gets pested,
So any body ever occured such problem. what could be the reason behind this and what is the solution.