How to copy an SD card to two drives on Mac — and verify it

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Why one drive isn't a backup

On set or back at the desk, the most dangerous moment is the one right before you format the card. If everything you shot exists in one place (a single SSD, a single hard drive), then that drive is your footage. There is no backup. There's just an original that happens to be on a disk instead of a card.

The industry shorthand for getting this right is the 3-2-1 rule: at least 3 copies of your data, on 2 different devices or media, with 1 copy offsite. You don't need to hit all of that on the cart. But you absolutely should have two verified copies before the card gets wiped. A drive plus the cloud is the easiest way to do that, because the second copy is automatically offsite.

The right way: copy footage to multiple drives at once

Dragging a card into Finder, waiting, then dragging it into a second drive is slow and unverified. It's also where most people give up and just keep one copy. The better workflow is an offload app that writes to two or more destinations in the same pass and checksums each one.

Copsy is built around that idea. You pick a primary external drive and a second destination, and it copies to both in parallel while reading the card once. The second destination can be another physical drive or a cloud (Google Drive or Dropbox), so your offsite copy is created automatically during the same offload, not as a separate chore later.

How to copy a card to two destinations with Copsy (step by step)

1. Plug in the card. Insert the SD, CFexpress or camera card. Copsy detects it by content and recognizes the source (Sony, ARRI, Blackmagic/BMD, RED, Canon, drones, audio — and it reads any card or volume).
2. Choose two destinations. Set an external drive as the primary target, then add a second one — another external drive, or Google Drive or Dropbox. Copsy copies to both at once.
3. Copy and verify. Start the offload. Copsy copies the footage, organizes it by date and source, and verifies every file on each destination with ASC-MHL checksums — so both copies are bit-for-bit identical to the card.
4. Confirm before you wipe. Wait for the verified confirmation (Copsy can ping you on Telegram when it's done). Only format the card once you have two verified copies — never before.

Tools that copy to multiple drives on Mac — honest comparison

You have a few real options for multi-destination, verified offloads on a Mac. Here's how Copsy compares to two genuinely good free/cheap ones.

Pricing and features change — figures above were last verified in June 2026. The DaVinci Resolve Clone Tool is genuinely free and verifies with xxHash64, but it doesn't auto-detect cards, copy to the cloud in parallel, auto-organize, or notify you, and you have to open Resolve. YoYotta is a powerful paid DIT app (LTO/LTFS) with a limited free "YoYottaID" tier. Check each vendor's site for current details.

Drive + cloud is the easiest two-copy setup

If you only have one external drive on hand, you can still hit "two copies, one offsite" the moment the card is offloaded: copy to the drive and to Google Drive or Dropbox at the same time. That covers two of the three failure modes above instantly. If the drive dies or gets dropped, the cloud copy survives, and vice versa.

This applies just as much to modern non-card workflows: an iPhone 15/16 Pro recording Apple ProRes to an external USB-C SSD, an Atomos Ninja recorder writing ProRes/BRAW to an SSD or CFast, or an Insta360 microSD full of raw clips that still need stitching. Copsy reads the SSD or card the same way and gives you two verified copies before anything gets reused.

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