Tigerstar: First death by Scourge, second death by Firestar
Hawkfrost: Both deaths by Brambleclaw
Antpelt: First death by Thistleclaw, second death by Ivypool
Darkstripe: First death by Graystripe, second death by Firestar
Ashfur: First death by Hollyleaf, second death by Bristlefrost
Brokenstar: Both deaths by Yellowfang
Darktail: First death by Onestar, second death by Violetshine and Needletail
Redwillow: First death by Blackstar, second death by drowning
Shredtail: First death unknown, second death by Lionblaze
Snowtuft: First death unknown, second death by Ashfur
Spottedleaf: First death by Clawface, second death by Mapleshade
I'm not sure if Bristlefrost counts.