Unfortunately, I do not think the 7000 had double exposure mode, although the manual mentions an Auto rewind stop function. It just doesn't tell you anything about it.
I have heard that it should be possible to fool it. If for instance you want to double expose frame 6, You take the pic then rewind. It should leave the film leader sticking out of the cassette. open the back (not in bright sun) and re thread the film back onto the sprocket exactly as you originally did (use a mark on the sprocket). Put the cap over the lens plus a dark cloth (just in case) and start shooting until you reach #5. Remove the cloth and cap and take your double exposure.
Not very professional but it will work, unless the camera rewinds the film entirely back into the cassette, in which case you will need a darkroom to get it out.
The best way by far is to digitize two frames and merge them in a good photo editor, or if you prefer film, get a Minolta 7, possibly the best film camera ever.