Are both memory cards necessary for the operation of the drone (one in the drone itself and the other in the RC)? I have looked in the manual and there’s no mention of the memory card necessity or even purpose in the RC.

No. In fact, no memory card is required for operating the drone - but of course you can't really store much in the internal memory.

The only usage I can find for using a memory card in the controller is being able to record the screen.

So, everything gets stored in the drone memory card then (in case one wants more space than what’s built I to the drone)?

The drone itself has very little storage capacity, so if you plan on taking photos or making videos you absolutely need to install a memory card. And really, using the camera is mostly why you'd get a drone to begin with

RC memory card is a waste imo.  You cannot download footage in hires from the drone

chillibadger Posted at 9-6 11:19
RC memory card is a waste imo.  You cannot download footage in hires from the drone

The slot in the RC is useful for keeping a spare memory card for the drone, in the unlikely event you might fill the first one

It's nice to have a memory card in RC to record  the screen recordings in case you have flyaway or crash your drone.

Blériot53 Posted at 9-6 11:36
The slot in the RC is useful for keeping a spare memory card for the drone, in the unlikely event you might fill the first one

Another good reason for having SD card in RC

GeirB Posted at 9-6 11:09
The drone itself has very little storage capacity, so if you plan on taking photos or making videos you absolutely need to install a memory card. And really, using the camera is mostly why you'd get a drone to begin with

I understand the usage of the car in the drone.  I was asking about the one in the RC itself.  

Raking Posted at 9-6 12:04
I understand the usage of the car in the drone.  I was asking about the one in the RC itself.

The one in the controller is for recording screen capture. You would probably only need 8 or 16 gig for that.

Goggles Pisano Posted at 9-6 11:48
Another good reason for having SD card in RC

One time I was glad I'd done that. To download data to my PC I remove the SD card from the drone into an SD card reader.  Left it in the PC when I went off to fly. Saved the day with the spare one in the RC

I use the one in the RC for screen recordings.  It also serves as an emergency back up in case I leave the one in the drone out by mistake.  Just have to take it out of the RC and put it into the drone and then ready to film and didn't have a wasted to trip to a filming site.

I got me two 128GB cards, one for the drone and the other for the RC ... sounds stupid, but when the drone's card is full, I can switch the cards and continue recording ;-)

I find this pretty handy, because storing these tiny cards in the bag is not my cup of tea.

Drone Jockey Posted at 9-6 13:16
I got me two 128GB cards, one for the drone and the other for the RC ... sounds stupid, but when the drone's card is full, I can switch the cards and continue recording ;-)

I find this pretty handy, because storing these tiny cards in the bag is not my cup of tea.

If you keep flying until your 128 GB card is full, you don't value your images.
How many eggs do you want to keep in one basket?
How much of your work are you prepared to lose in one incident?

Labroides Posted at 9-6 13:52
If you keep flying until your 128 GB card is full, you don't value your images.
How many eggs do you want to keep in one basket?
How much of your work are you prepared to lose in one incident?

Yeah, 64GB might have been enough, but hey, these cards are pretty cheap and I usually keep collecting while "on the road" and eliminate the crap at home ;-)

Labroides Posted at 9-6 13:52
If you keep flying until your 128 GB card is full, you don't value your images.
How many eggs do you want to keep in one basket?
How much of your work are you prepared to lose in one incident?

Some baskets are larger than others.

KLRSKIR Posted at 9-6 15:10
Some baskets are larger than others.

And your point is ?

You'll also get low res cached video on the RC SD card.

Labroides Posted at 9-7 01:03
And your point is ?

Since 2016, filling up many microSDXC cards on vacations, work, etc., I've never worried about nor have I lost a card due to crash, corruption or the like. Sure, the odds are against you if you pile everything onto a 256GB card without dumping to external.

I guess I'm lucky! That's my point.

Have you guys ever worked out how to automatically copy a SD card to a large HDD?

fans574cda0a Posted at 9-7 08:07
Have you guys ever worked out how to automatically copy a SD card to a large HDD?

What do you mean by automatically copy? Like to an external HD?

Hello there Raking. Thank you for reaching out and for giving out these information. The microSD card slot in the DJI RC is used to preview copies of the photos and videos that you have captured using your DJI Mini 3 Pro. While the microSD card placed on the DJI Mini 3 Pro Drone will save and record all photos and video clips in high quality. Thank you.

Drone Jockey Posted at 9-6 13:16
I got me two 128GB cards, one for the drone and the other for the RC ... sounds stupid, but when the drone's card is full, I can switch the cards and continue recording ;-)

I find this pretty handy, because storing these tiny cards in the bag is not my cup of tea.

Plus they are pennies to buy these days.