Sounds like what you are proposing will not work.
Should a dual 2 ohm have a different sound than a dual 4 ohm, on paper YES, will you hear the difference??
There are some speakers who may have similar parameters in both 4 and 2 ohm, but most don't and thus will look different on paper or in any Box builder program.
Different ohm loads should result in the speakers sharing the power diferently thus have different and / or louder sound from one to another of the 3.
Why not run 2 dual 2 ohm subs in parallel with the 2 ohm voice coils in series. 2+2=4 them 1/4+1/4=1/R, R=2
This means the your amps total power will be divided by 2 speakers. This will mean more power to each than if you divided the same power over 3 speakers.
Ex. 600 w @ 2 ohm or 300 w per 2 speakers or 200 w per 3 speakers.
In that most amps not are stable to 2 ohm bridge to even think about below 2 ohms, you will want your 3 speakers to have a ohm load greater than or equal to 2 ohms. Your best setup for 3 speakers using 2 or 4 ohm voice coils will result in a 2.33 ohm load and each speaker will see less than 200 w for the example above.
Mean while someone with the same speakers and amp will sound better and louder than you 3 speakers with same amp because his subs work together (being the same) and he has more power to each sub.
Anthony B. Davis
2Deep2 Silver SVT
2002 IASCA SQ Ult Ama 601+ World Champion runner up
2002 SLAP dBQ Champion
2000 USAC SQ World Champion
2002 USACi SQ World Champion