Okay, so I was thinking and I came up with this crazy idea:
What if there were fertility philters?
If you could buy these things in the scale shop, wouldn't it be great to have your female produce 2 eggs when you used this on her? Of course, it would not be the cheapest thing in the scale shop, and it might be possible to have it in the diamond shop. But doesn't that sound cool? Feel free to share your thoughts here!

This was actually just mentioned by Krin:

Link: https://www.sylestia.com/forums/?thread=17390&page=1#5 Author: Krinadon Time Posted: 9/28/2014 at 12:04 AM I think a feature like this would be a bit game breaking. Either I'd have to spent a bunch of time building a bulky restricting system or I could just add it like so and then you could breed 100 offspring from a pair in a single day. Recovery times are kinda one of the few limitations of the game that I think are necessary. However, we are thinking of adding some type of fertility philter to the new scale shop.

It's in this thread

edit to clarify: I'm only referring to the last sentence of this quote. The rest of the quote is referring to a suggestion for a philter to reduce the breeding cooldown, which Krin says here won't likely happen. I understand the last sentence to mean that Krin and Fai are already looking into a fertility philter similar to the one being suggested, though it's possible it could be some other kind of fertility philter.

Mikazukichan, your quote is not very accurate. The reply of Krin you quoted was in regards to philters reducing the recovery time of females. Okapilover7 is suggesting philters that would allow for twins to be born.

This suggestion has been made: http://www.sylestia.com/forums/?thread=14663
of which the reply from Krin at that time was:

Link: https://www.sylestia.com/forums/?thread=14663&page=1#3 Author: Krinadon Time Posted: 6/7/2014 at 9:11 AM We may add something like this after we make the changes to the breeding system that we're planning. But atm, the issue is that there are too many pets being bred so adding this now would just amplify the issue. Also, you don't have to ping me in the Suggestion Box forum. We read every thread already. =)

I'm sorry that the quote seemed inaccurate. I was only referring to the last sentence of the quote and should have made that clearer. I'm fairly sure that a 'fertility philter' as krin was referring to it had to do with twins as he said that there wouldn't be something to reduce the breeding cooldown (which is what the majority of the quote is talking about). I could be wrong, however.

Ahh... okay. So seemed like there was some misunderstanding =P

I'm thinking the same. The fertility philter could be for making twins.
But we won't know till it actually comes out. =3
(I heard there might be infertility philters though, to stop pets from breeding. Not sure if that's coming out.)