When psychics explore things as other timelines, is this just another way of looking at so-called past lives that are happening in the Now?

Yes, this is the case. All lives are occurring simultaneously in the Now. So in a sense, while the separate lives you think of as timelines have their own past, present, and future, they are in parallel and all is concurrent. This is complex and difficult to conceive of and hold in the mind, but is very, very, true. So this is not something unique or different from the paradigm you address, but simply differing terminology.