I guess you are using two separate flower tents for spacing reasons so it is what it is.
The issue you will have in linking both tents is if you try to link them in series. You need to use a Y splitter to pull air out from both separately. This is because if you pull air from one, to the next, the last tent will have to take all the humidity and heat from the first flower tent. That could be very bad for either tent for many reasons. When it is warmer outside, you will have to run the fan so hard to lower temp/humidity in last tent, that the first tent runs at a constant lower temp, and that will hurt ambient, canopy, root temps and humidity of the first tent. Also, if you have any mold problems in the first tent, the second tent gets it too. In winter all of the cold air has to pass thorugh the first tent, so that means it will never do as well as the last tent due to temps.
Connecting a veg tent to a flower tent is not near as bad, since you don't get mold in veging plants, passing it to the flower tent, or not that I am aware of. Veg tents can also take a lot more heat and humidity so you have more room to play with in warmer days. Perpetual in this way also saves on needing seeds, just cuttings from cuttings. Veg tent temps can be a little lower becuase of this, however their are ways to fix that. It will slightly impact veg growth none the less, but saves on having completely individual tents, requiring double of the equipment.
If you decide to keep going with dual flower tents I personally recommend this. Use a Y splitter onto a 8" out-take, german out-take fans are good. Make sure tubing is same length to both tents, and same elevations etc. This will help ensure equal flow. Use passive intakes, but ensure they are the same in both tents, again for equal flow (I assume both tents are the exact same size/brand also?). If that is true, then you can do this.
By a volt step fan speed operator, and also buy an ink-bird temp control unit. Both tents need the exact same heating system, or should be in the same room with the exact same ingoing heat. This is important as you are trying to get 2 for one here from the volt and ink controller.
The inkbird will read the temp in one tent (hopefully the other is very similar range) and it will only turn on the out-take if the temp gets to your high range. The Volt step controller then controlls the big 8 inch fan, where you can set it's min and max speed (setting 1-5). Setting both min and max to 2, will mean when the out take kicks in, it will reduce temp and humidity slowly. The ink-bird will then shut off the fan when the lower temp is reached. The ink-bird also has the heating option, if temp goes too low it will switch to your heaters. This automation means your out-take and heaters are not running 24/7, and saves a hell of a lot of W. It also means you use more of your light heat.
The volt stepper and ink-bird will set you back around £300. However it will pay off very quickly. I can only roughly guess that it will save 20 to 30% of heating and out-take W, for ever. However you still need around 1k of heating potential, 500W per tent or 1k for room. You do need to account for the coldest months at lights off. Do not cheap out on lights off heating ability. You may be able to get away with 300W per tent, it really depends on were your room is, and what upper temps you wish to run. With Led you really want an ambient around the 80F range. Some go higher, some lower, but 80F is my minimum recommended.
Humidity control is a whole other factor. I don't know how you will achieve this with two flower tents, not withought requiring 2 de-huey. You can't put them outside tents in the above situation. Although you could work with an independent 4 or 6 inch circulation ''intake'' fan between the two tents and the room (single de-huey in the room). That will circulate humidity through tents/room and is probably the cheapest all in way you will be able to do it. Unless somebody has a better idea.
