I did some tests but I wasn't able to reproduce it. All Terminal clients in general have some quirks with resizing. Depending on the scenario, different clients behave differently. And then there's also the server behavior. When the client resizes, the server gets notified and can adapt the shell accordingly (useful when you are using UI apps like midnight commander). So there's also a chance that the server is messing up the display.
Can you please clarify which Terminal plugin you are using (rebex or putty based)? In case of PuTTY, there's nothing we can do about it. If this behavior is in rebex, we can contact the vendor and see if they can improve the behavior. For this, it would be helpful if we have some detailed repro steps - maybe a script which produces the kind of output which clearly demonstrates the misbehavior. To rule out the server side, can you try to reproduce the issue on different systems?
Make a connection to unix. Make another connection to unix. Drag and drop so that the two tabs are in separate rows. If the output has filled the visible area, The command line will sometimes be duplicated or erroneous characters will appear at the bottom. Fiddling with resizing will sometimes fix the issue or make it worse.
Has anyone seen this? The bottom line here is an artifact. The solid green cursor is the actual command line. (hostname covered up with blue for security).