I own two Echo Dots and would like to create a IFTTT recipe that is only active on one device. Is this possible?
Only if you put the Dots in separate accounts.
The problem with IFTTT is that you can only connect to the Alexa services once. Vice versa the Alexa App doesn't allow differentiating between several Echo Dots for specific Skills. (Just try it, there are literally no settings on either side to help you out.)
To achieve a recipe that's only active on one device you'd have to use two Amazon Accounts. Those can then both be connected to the same IFTTT account. (I haven't tested that. Maybe you need two of those as well.)
Problematically if you use two Echo Dots in separate Accounts (that are not somehow connected to form a household) you'll likely trigger both at the same time. As far as I know the Echo Spatial Perception only works if the Echos are in the same account. So using separate accounts would rob you of that feature and likely have two Echos react. One failing to provide a proper answer because it's not connected to your IFTTT Recipe.
To solve that you could use different wake words on the Echos. (Echo One reacts to "Alexa", Echo Two in the other account reacts to "Computer".) That means two Echos, two Amazon accounts, two wake words. You'll have to judge if that IFTTT Recipe of yours is that important to only work on one Echo.