Raising animals in Raising cows and chickens from birth doesn't necessarily yield any mechanical benefit but when the game briefly glitches, it can result in double the produce.
Posted to Reddit by Nosleepanymoreuwu, the player revealed that their attempt to hatch a 
Void Egg became more fruitful when a glitch resulted in the item spawning an additional 
Void Chicken.
The community widely believes the incident to have been the result of a bug since animals can't traditionally have twins in Stardew Valley and Nosleepanymoreuwu was only prompted to provide a name for one of the chicks. Having said that, both critters seem to function normally despite sharing an identity, leading many to label the discovery as the first-ever documented case of animal twins in the game.
Twins Should Be Made Official
It Could Be An Extremely Exciting Event
Given the sheer amount of focus on raising fauna. It could also be tweaked to ensure that having twins is incredibly rare, so players can feel a special excitement when they do wake up to find two babies instead of one.
Mechanically speaking, it likely wouldn't change much about Stardew Valley's gameplay loop. At the most, it would simply eliminate the need to wait for an animal to have two babies over an extended period. It seems like a very small addition that could go a long way making the game even better.
10 Things To Do First When Stardew Valley 1.6 Comes To Consoles
Stardew Valley is finally bringing the massive 1.6 patch to consoles, which will allow these players to experience all of its changes and goodies.
Could Stardew Valley Ever Get Twins?
It's Certainly A Possibility
ConcernedApe has made it clear that Stardew Valley will be around for a long time since he's constantly working on new patches that flesh out the farming RPG. Whether or not animal twins are a priority for the creator remains to be seen but he has been known to listen to the community's demands. If enough players request such a feature, there's a good chance it could be added in a future update.
Source: Nosleepanymoreuwu/Reddit
