Decided to try a little writing with this puzzle, so forgive the bit of extra length. Hopefully the story is entertaining enough to forgive a tiny bit of extra length ;)
"Alex is almost three, and his little brother there is two." Chris explained, as the squad-mates made appropriate comments about how adorable the photo of Chris' wife and two children was.
"Linda hated me accepting this tour, she keeps telling me I better take care of myself so I can be there when Alex graduates. I've missed her and the kids so much lately; I'm thinking when I get home next month I'll tell her she's won and I'll find another job. I'm not sure what I could do, been a military brat as long as I can remember, but I guess I could be a police officer or something. It would be nice to actually get to see the kids every day. Linda's been wanting another child, I wouldn't mind a little girl..."
Chris' planning was interrupted by the sound of an explosion nearby. An ambush! The little squad of five saw over a dozen men coming out of hiding, they were seriously outnumbered! Chris ran to grab a rifle and return fire, but never made it before collapsing in pain from a belly shot. The squad managed to kill two of their attackers before the last man fell. Five casualties to two, for all their training they hadn't even manage to return half the damage inflicted on them, an inglorious battle in the end, cursed ambushes! Chris' last thought before everything went black was of little Alex and that graduation Linda had wanted them to attend together.
Linda had always feared the day would come when a solemn soldier knocked on her door instead of Chris. The soldier was dignified and sympathetic, offering his condolences and best wishes, but that didn't make it any better. They wouldn't even tell Linda exactly how it happened, they had to protect "military intelligence" apparently. No just some fancy terms like "enemy action" and "regrettable casualties". Not that it really mattered, what mattered was someone had shot Chris and all the fellow soldiers Chris had cared for, and no man had survived the attack. Linda didn't know what to do, how would she explain this to the kids?
Time went by, and the little family kept living after the tragedy. The memory of the visit of a soldier in the night never left Linda, though it got easier with time. The widow never got over her love for Chris, never remarrying again or even even dating again. Alex and his brother Josh grew up without a father to love or care for them, the children were so young they didn't even remember what it had been like to have a father, but still they grew...
Almost 20 years Later Lisa stood in the college auditorium, filled with soon to be graduates. Alex stood at the front of them all, giving the valedictorian speech. He told the graduates of the father he couldn't remember that died when he was a child, and shared the story of Chris' last battle, telling the listeners how life may never go as planned. But he ended his story with a message of hope and perseverance and the ability to survive and grow with whatever hardship life throws at you.
After the ceremony Linda hugged her son, telling him how proud she was. Lisa, Alex's little sister, seemed more interested in listening to her music and checking out the college she was planning to be attending soon then Alex or his speech, but she still gave him the obligatory congratulations.
"Well, Lisa may be too busy plotting to take over this place once you leave to have listened, but I'll say I was impressed with that speech. But I think you gave me way to much credit" said Chris. Not that Chris minded too much, after all how could a parent be upset on the day of their child's graduation? This was a date Chris had been promising Linda to attend for two decades, and it was worth the wait.
Whats happening here, has the ghost of Alex's dead dad stopped in to visit? A good answer should take the time to explain all the apparent discrepancies they can.
Hints to narrow down possible answers are below.
There are not two Chrises, There is only one person with each name in the story
The military did not make a mistake (other then falling for an ambush I suppose), they provided accurate information
The ambush was real, no military exercise, dreams, or other simulations.
Chris was not brought back from the dead, no ghosts, clones, or undead vampires either.