If "...the seed is polyembryonic, i.e. has many embryos, it will come true. I asked what it would look like if it were polyembryonic. Carl said that the various embryos would be convoluted upon each other. If it is mono-embryonic there will be one embryo with two distinct cotyledons."

See "Citrus propagation" - https://www.ultimatecitrus.com/pdf/tncitrus.htm 

All Key lime seedlings are true (same as the mother tree). Always true no matter whether the seed sends up one seedling or multiple seedlings per seed.

Thats exactly what i wanted to know silica. Thanks guys

That is good to know. I've wondered about this myself. I sprouted key lime seeds this fall and all were polyembrionic. However, some were much bigger and the remainder more like runts. I separated them all and the runts died after a couple of months of stunted growth. I do have one semi-runt that continues to grow though. What causes those smaller, weaker plants? As clones, they should all be identical, right?