You also have to remember that the fish you've just bought from a store are juveniles. Behaviours can and will change as they grow and mature, especially once they reach breeding age and become more territorial and interested in potentially breeding.
A lot of people buy fish, come here and say "but I've had them for months and they all get along really well!" not accounting for the fact the fish are all still juveniles, and their adult behaviours haven't kicked in yet. Then return when disaster happens.
Not saying your mixing yoyos with dwarf chains will necessarily lead to disaster! As
@anewbie said, you can sometimes mix different species of botiid loach in the same tank without issues, or with minimal issues, if you know what you're doing, the tank is large enough, and- crucially - if each species has enough of the same species.
Botiid loaches are intelligent, curious, boisterous, and social fish, and as others said, your yoyos will grow much larger than the dwarf chain, and might well bully them, along with bullying each other. My dad kept two yoyos in his tank for years, and looking back now with a more experienced and knowledgeable eye, and I can see how stressful that was for them. Because one will always be dominant over the other, and make sure the other knows it. He had a large, chunky female, and a smaller, sleeker male, and I loved when I visited and watched the tank and they emerged from their hiding spots! Loved watching those guys.
But one, the bigger female, actually, would often be chased away, aggressively, by the more dominant male. She'd also often "grey out", which means they're super stressed. With a larger group of the same species, that dominance and aggression is spread out among the group, who have established a pecking order, and the female, even if she was at the bottom of the pecking order, would have still had breaks from that aggression, since the male above her would also have to deal with the ones above HIM in the pecking order, you see what I mean?
But because it was just the two of them, it was relentless, and they didn't have a great quality of life, sadly.
Yoyos are one of my favourites, but when i get some, I want a minimum of five. They need a minimum of five of their own species, and they won't just form a social group with the dwarf chains, I'm sorry to say. Fish know what their own species are, and dwarf chains are so much smaller and more shy.
I don't know the size of the tank we're talking about here, but if possible, I'd recommending having at least 5-6 dwarf chains, and 5-6 yoyos, with a good amount of hiding spaces, hardscape and plants over the floor to provide places to hide and establish territories. Can make things like slate caves and areas, section of corners with plants, things that break lines of site, and give the fish places to rest, hide away and avoid when wanted, and places for these active and curious fish to explore. They love to squeeze into gaps (watch your filter intake! Had to rescue one of dad's yoyos when the outer sponge part of the filter intake fell off, and one of the yoyos had squeezed itself into the intake tube!), so things like PVC pipe and slate caves are welcomed by them.
The pages on the species on Seriously Fish, especially compatibility sections, will tell you a lot, worth reading the pages on both species. For example they say the same about their social needs:
(from Seriously Fish)
"
Botia spp. are
gregarious, form complex social hierarchies and should be maintained in groups of at least 5 or 6 specimens, preferably 10 or more.
When kept singly they can become withdrawn or aggressive towards similarly-shaped fishes, and if only a
pair or trio are purchased the dominant individual may stress the other(s) to the extent that they stop feeding."
