Pretty sure Atlantis was this way too. It's how I have my Atlantis drop-targets currently, FWIW.

Doubled up on an Out of Sight, still worked perfect. Don't want to snap a drop target if you can help it.

Also keeps the ball from getting stuck under the rubber in the target slot, especially on long spans.

I think the actual reason would be to protect the scoring switch behind the drop targets. All the games cited in the thread use five-banks. Five inches is a considerable distance to stretch a rubber with no protection in the middle, and I personally would never do it; I'd add an additional centre post instead.

Or just use one long target like Stern now uses

Is there anything better than classic tombstone drop targets?? Mmmm hmmmmm. Please someone offer these up for all games that had them.

That is all.

The reasoning I've heard is that on wide banks the rubber can stretch enough to let a ball under. I've seen it happen on my Far Out numerous times. Probably not to protect the drop targets

Not just a concern on EMs either. According to the IPDB, Getaway was known for blowing the MPU board if a ball got stuck under a slingshot, broke the bulb, and created a short between the switch and the bulb filament. Has this ever happened to anyone here?

Can a ball potentially be trapped if it hits the rubber as the targets are resetting? The situation can occur on Volley - dropping the last of all 15 targets (say, on the green bank) will trigger the target reset, meanwhile the ball caroms up to the lowered yellow target area and strikes the rubber just as the targets are coming up. I’ve seen the ball hit the glass in this situation, I can imagine if the ball hits a weak or loose rubber it might be trapped behind the rising targets.

Tim Arnold advocated this in one of his videos as a way to make the drop targets last longer.

My Checkpoint is doubled up behind both sets of drop targets.The posts have grooves for them.

The other benefit of double rings on Gottlieb drop targets, beyond protecting the drop targets themselves, is to protect the playfield plastics. A weak backing to the drop target will allow the ball to carom upwards and break playfield plastics. The upper drop target bank on El Dorado, the upper banks on Countdown, and the single target bank on Jacks Open are all prime examples where double rings will benefit the game and playfield plastics.

Basically any game that has a direct straight on shot to the drop targets is a good candidate for this. Glancing shots like the side DT banks on Countdown are not as succeptible.

I've tried both and do not like the way the ball rebounds from the double rubber. It sometimes resulted in ball bounce.