Three chute doors had different hardware, a different faceplate pretty much. The bottom door would be different in the fact that it would be missing the center coin reject hole if the door was on a 2-chute system, HOWEVER, probably 50% of the doors filled these with spacers rather than being a new molded door, likely to get rid of old Gottlieb overstock.

Two chute hardware used the typical coinage of what you described in the late 60's, but your game would typically be set up for 25c/2 plays across both entries. However, I feel like you should possibly have the option to still change them to the old style. Hmm...

Late 60's 3-chute pricing, if you weren't using 2-chute hardware (which only eliminates the nickel pricing and would typically be 10c/1 play, 25c/3 plays)

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Early-mid 70's pricing, double 25/2 plays (You sometimes see double 25/3 plays settings from the more generous operators)

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AHA, now I see your predicament even clearer.

Gottlieb never had "real" support for dimes, because rather than giving you multiple credits for one coin, it would be the other way around, which was giving you one credit for multiple coins (nickels). How was Gottlieb to track for many nickels you had already put in? While there was a few different solutions (Williams probably had the best one, or was it Bally), Gottlieb took the route of using something on the coin mech to only make it trigger the game's circuitry once every other coin, I can explain how it works but that's a whole different story. So basically, if you had a 3-chute door the two chutes closest next to each other would be both set on a shared "1 coin/1 play" setting, because remember, although it wants two nickels the game is only really notified that you put money in once you've deposited both coins, so to be clear we can call that "1 credit/1 play" as 2 nickels = 1 credit just as one dime = 1 credit.

For 2-chute doors (accepting both dimes and quarters), the extra chute adjustment would be to adjust your 25c chute and how many credits a player should get for 25c. It is very very rare to see any other denomination installed in this slot and I do not think it was expected by Gottlieb, last I checked you can't set this chute to accept 1 coin per play, only the left chute.

I do not remember the left chute having an adjustment in the 60's games because it was pretty much expected you would never want to give more than one play for a dime, but then, one the 70's came and both slots were usually used for quarters starting around 1971-1972, you then would need to boost the setting to "1 coin/2 plays" after all so I'm thinking there must be an adjustment in your game somewhere. My November 1972 Gottlieb Wild Life is set on quarter play and I do not imagine the typical pricing transition was between these two games - although they should in theory support both as some operators really hung onto to the cheap pricing for a while. It was rare, but definitely happened.

Well, they had to be wired that way in-case somebody did want to utilize the old coinage settings, and was probably somewhat of a standard in Gottlieb wiring anyways even if that wasn't the case, where it was probably more convenient to keep doing it that way than put work into redesigning the circuit (and also assuring sure it worked consistently, etc.) to save minimal effort and wiring.

The two slot standard can be seen all the way to the newest games of today and all through arcade machines from even earlier than the popular ones of the 70's and 80's to today - if one coin slot gets jammed up you don't want to lose your entire revenue until you fix it, you want to have a second one to take the money in while your other one is down. Basically a backup, except both function when both are working rather than one being solely a backup.