That depends on whether they need service or repair work. For machines needing repair, it’s often not worth it.
Double Trouble
Dual or double-cassette machines have two cassette bays and were generally the cheapest cassette decks of their time, sold at the end of the cassette golden era. Cassette deck maintenance can be some of the most labour-intensive work. How many cassette deck mechanisms are in a double cassette deck? That’s right, there are two, and they are not usually the nice ones to work on. See the problem?
This doubling of mechanisms means double the heads, double the belts, double the capstans and pinch-rollers, double the cleaning and double the disassembly and reassembly. Doubling the already time-consuming workload usually means more work than these decks are worth, to most people anyway. Ultimately, an owner will need to decide, but I generally avoid working on dual cassette machines for these reasons.
Viability vs Lovability
If both decks need only standard maintenance, then yes, this is probably worth doing. If both decks need repair in the form of idlers, belt replacement, or other deep service work, this is generally something to avoid unless cost is not a concern. The opposite is true of good single-deck machines of course and I still work on those. Single-deck machines are almost always built much better, perform better and are nicer to work on.
