Subdivided apartments?

I’ve been looking for an apartment in Taipei, and I often find that some of them are actually one single address divided into 2 different listings? So you can imagine a 3 bedroom 2 living room divided into a 1 bedroom 1 living room + 2 bedroom 1 living room. There is one main door, and as soon as you open it there are 2 separate doors leading to the 2 individual “units”. There is no common living space between these two units, but both of them have the same address (not even A/B separation). Is this legal? I can understand that this makes the landlord more money, but just wanted to make sure things are alright.

What are you looking for in particular? What is your budget? What districts?

In some cases it’s legal. Don’t know the entire details.

It is common, not sure about legal.