It’s an option, although we generally don’t recommend it. Each oil has its own chemical composition, flavor profile, and smoke point – and they might be quite different from each other or even incompatible, in some cases.
If you do opt to mix oils, here are some important reminders:
ALWAYS, ALWAYS, ALWAYS have the flame OFF if/when adding oil. (If any oil splashes or bubbles out into the flame, it can ignite.)
If combining two types of oil, be sure you know the smoke points of both.
Ideally, they’ll be fairly similar – and then be sure you keep your frying temperature UNDER WHICHEVER SMOKE POINT IS LOWER.
Here is a link to a 2019 article on smoke points from Savory Simple that we like:  Understanding The Smoke Point of Cooking Oils and Fats – Savory Simple
This article lists the smoke point of bacon grease at 400°F and peanut oil at 450°F – and we suggest keeping the oil at 375°F when frying a turkey, so they should be okay together.
Do NOT use BUTTER. Its smoke point is too low to be appropriate for deep frying.
For most people, bacon grease has a distinctive and preferred flavor profile. If you need to add another oil, we suggest you choose one with a neutral flavor.