Please see the most recent updates in the "Where did the .com name go?" thread. Posts number 16 and 17.
Please see this thread for updates. Update Thread
SOH ADMINISTRATIONIt is a DP entry of ",," when the damage is 100% but I forget where.
Okay, found it.
"effect.4=100,BREAK,,"
"effect.0=95,LIBRARY,,
effect.1=100,DEATH,,"
If you do not have two commas after the break for 100% in the DP or for "death" I think, it splits the plane into two planes instead of just blowing up or pilot bailing.
At least I think that is what was said. I am sure someone that REALLY knows will come on and correct me.
I have this problem with just a couple of mz aircraft, but cannot remember which ones off of the top of my head.
As DD said it has to do with how the sim handles the DP. There should be NO number after the commas. I had started a thread on this and it was discussed and help me rid my game of this annoying cloning. Had the same with the MZ planes (which are great!). Am not at my home computer right now so can't send the thread location but it is (hopefully) still here somewhere.
Did a search and found the answer here; http://www.sim-outhouse.com/sohforums/showthread.php?t=449&highlight=tips
Scroll down to October 4th.
A final note.
You'll notice that each EFFECTS system looks somewhat like this one, taken from the stock Zero:
; System = Nose Structure
effect.0=10,LIBRARY,fx_smkpuff_s,
effect.1=30,LIBRARY,fx_engfire_s,
effect.2=60,LIBRARY,fx_engfire_m,
effect.3=95,LIBRARY,fx_airexpl_l,
effect.4=100,BREAK,6, <--------This "6", or whatever number you find, is the problem.
You have to remove the BREAK number from each and every EFFECTS system. The above line would then read:
effect.4=100,BREAK,,
The BREAK number tells the sim what breakaway part to model when specific amounts of damage have occured. If the model wasn't built with those breakaway parts, the sim will spawn a complete model instead. Many add-ons' are like this because adding breakaway parts involves difficult SCASM editing.
Thanks everyone. I am trying this now.

I joined after this date, but not long ago there was another discussion and some things to edit were given. My particular problem was Yashico-san's Ai B-29s would split in two and one half keeps flying. I did the edit and found that this seemed to make the planes invulnerable and I just changed B-29s. I also got a .dp for the Betty bomber at Flightsim.com that now has wing fuel tanks, and they blow up real good.
Bones
...Why do some planes do that?
I remember this from many years ago - I believe it's to do with the product some people use to build their aircraft; the problem seems to stem from Abacus' "Flight Design Studio" which a lot of cfs2 plane buiulders used to build their aircraft.
If you study what happens after the plane morphs into 2 you will see that it closely resembles the graphic of a stock aircraft losing its wing. The morphed plane spins crazily as if its attached to the original destroyed plane - just like the blown off wing effect!!!
I remember contacting Abacus back in around 2003 on this, and they replied that it was a bug with their product purely relating to cfs2, but said it could be got around via modelling the "broken wing" and altering the root directory or something, but never actually told me how!
Personally I don't use these problem planes except to fly. Obviously in the case of some, like the otherwise excellent mz planes, there is often no other show in town.
I've even got aircraft installed purely to fly against so that I can be sure this annoying thing doesn't occur.
I've found that some of the bombers I've downloaded and installed are pretty invulnerable too;
The Ki-21 Sally is a prime example, I built a mission set over Arakan in Burma 43. Spitfire V's intercept formations of Ki-21-11a/b's escorted by stock Oscars.
Man I knocked 7 bells out of those bombers, and the Spitty had cannon. There were explosions, fireworks, pyrotechnics and enough smoke to blanket London. But those pesky Sally's just kept trundling along, and to add insult to injury some of the fires even went out!
I mean Jap planes aren't suppose to behave like this! If only our bombers had that resilience we'd never of lost any over Germany..........
Why do some planes do that?

Makes sense - guess we all juggle around the various planes to see what's best for what situation. Fortunately there's usually a choice thanks to all those talented guys out there. Yep Jap planes were good burners for a considerablr portion of the war, yet these seem almost indestructable in some cases.
I wonder, would the firepower of the fighter (as decided by the builder) have any bearing on damage caused? Or is every gun automatically the same regardless of fighter as in il-2?
Funny enough my Sally's and Lily's have behaved themselves (you have to treat em like ladies), though I did isolate a problem which I intitially thought was the Ki-21-11b, but in the end turned out to be the Spitfire V111 wearing a RAF/SEAC marks, which was a bit of a bummer as I've been unable to find another. Hence using Spit V's in 43.