
This isn’t a problem with USB as it just natively supports it.

The caveat is that in order to be able to use two drives at the same time over eSATA, your controller card needs to be able to support the port multiplier function. The BlacX Duet has all of this and one caveat for using two drives with eSATA. While many new enclosures feature both eSATA and USB, not many feature two hard drive slots. The two LED’s on the power button double as a power light and activity lights. It means they’re not cheaping out on their cables. The eSATA cable that’s included is a rather heavy gauge cable. The BlacX Duet comes with everything you need to start hooking up drives. The front of box has a nice mock up of the docking station in action while the back lists the features and specifications. Supports eSATA Transfer Speed up to 3Gbps.Compact Docking Station Design maximizes Heat Dissipation & Exhaust.

Hot-Swap Capability for Rapid Multi HDDs Access & Exchange.Copy & Transfer data between Hard Drives & Computers.All 2.5” or 3.5” SATA HDD up to 2TB (per slot)
