I had been doing that with Python and Processing (Java based), but have dropped Python for now. Processing is part of a course I am doing which will lead to a Java course. (that is also why I have been rather quiet here)
it worked in the beginning but at the moment with more complex problems to solve it is difficult to maintain.
my advice would be to get proficient in one and then go back to the other. you really pick it up that much faster!
Yes, but it can be hard to be sure that you can tell them apart.
Best to switch back and forth.
Learn Python's basics, practice them for a while.
Then learn Java's basics, practice them for a while.
Study Python's topic XY, practice it for a while.
Now study XY in Java.