I have Anabella and Claribella but thats intentional cause they're twins. I also have Cameroon and Koff for the 'k' sound, Valdo and Vance though i might get a different name for valdo, and Morel and Murfie :P
All my pets are named after languages. Most of the "mainstream" ones are already taken by other users but there are still plenty in the world to choose from.
... omg, I just realized that I have a crapload of real word names.
English: Gingerbread, Elysium, Dachshund and soon, once I reach my 4th Subetaversary, the lovely Jam (kindly held in the meantime by ).
Foreign languages: Gioia (joy in Italian), Solsken (sunshine in Swedish), Sampaguita (a variety of jasmine in Filipino) and Diamantes (diamond in... Spanish if I remember correctly).
I also have Laetitia, Agrippina and Alix, which are real names. Salyra, Galatius and Liekiiri are names I made up. Songbreeze is my only pet named after a character, in this case Songbreeze from Brian Jacques' Marlfox. :P
[edit] I have 4 pets that start with S. Did not realize that... hm.
Gwyneth and Griffith are easily my most similar two. I do have a lot with similar endings though - Pattyn, Carolyn, Finnegan, Elton, and then Remy, Whitney, Tessie, Briony, Rickie, McKenzie. I used to have Cydney as well but Cydney and Whitney were just too much

Gouta, Nota, Lokinta, Qualta, Heiltha--- They all end in a I guess xD
Kesare and Sekare are probably the easiest two to spot of mine, the only difference is the letters K and S are swapped. It was intentional, they were meant as a couple.
Aside from that, most of my names are various real-word names. I like real words. I have two color names, Crimson and White. Technically three if you want to count Cinereous (meaning 'of a dark or ashen color') but who ever uses that word in normal conversation? I'd have more if I could, I love me some colors. I have a thing for 'destructive' names, especially weapons, see: Death, Gun, Axe, Katana and Virus. Apparently I also like names that end is 'th' because I have South, Death and Sytalith. Had I the opportunity there's several more '-th' names I'd be happy to add to my family. And then there's just my plethora of object-names. Nouns I suppose they'd be, though my parts of speech fail me at the moment. Of the ones that haven't already been mentioned there's: Ball, Prophecy, Mockingbird, Collar, Contrail and Nite.
Zinnober Tantalized Zavedi Tizona Utisz
...I really like that letter...
Well, I have Seventh, Amuse, Determination, Accountableness, Tryndehi, Tiiqi, Mountennette, Erynn, Needlessness, Tinble, and Hylia.
Seventh, Amuse, Determination, Accountableness, and Needlessness are all real words.
Accountableness, Tiiqi, Mountennette, Erynn, and Needlessness all have double letters.
Tryndehi, Tiiqi, and Tinble all start with T.
Tryndehi and Tiiqi end with an E sound.
Determination and Erynn both end with an N sound.
Erynn and Tinble are both real names(well, Erynn is an unusual spelling).
I think that's about it. Easy to find similarities between 11 pets, I guess.