It also could be the firmware, maybe a bit more polished in mi pad 3. The fact that it shows 2,1 ghz doesn't imply it runs like that. Current XD shows 1,8 ghz and runs 1,4 in stock firmware, it needs my kernel to go higher. Anyhow, difference is minimal, and benchhmarks are just orientative. Device is also a proto so It's a bit soon to jump into conclussions. Another teclast device that use the same SoC also score a bit lower than mi pad 3. I think that CPU wise are good scores, mainly in single core which is what most emus use (my shield k1 is about 1100 in single core, and XD is about 900 with 1,8 ghz overclocked, so it's some improvement) . Maybe with root and cpu control scores would be a bit higher. Shield tab has a much better GPU though (and with vulkan).
The mtk8176 is mid range SoC, so I wouldn't expect miracles, it's closer to a snapdragon 652 or RK3399 than to a snapdragon 820 or higher.
The best benchmark anyhow is just testing emus, PPSSPP seems to run better, yaba sanshiro is a doubt (I'll test it when I get mine), or dolphin. Though I wouldn't expect dolphin to be great except less demanding games (wind waker luigi mansions or mario kart)