j3445 and 2x2gb ram

In the manual you can found :

1.2 Specications
Platform • Mini-ITX Form Factor
• Solid Capacitor design
CPU • Intel® Quad-Core Processor J3455 (up to 2.3 GHz)
(for J3455B-ITX)
• Intel® Dual-Core Processor J3355 (up to 2.5 GHz)
(for J3355B-ITX)
Memory • Dual Channel DDR3/DDR3L Memory Technology
• 2 x DDR3/DDR3L SO-DIMM Slots
* 2GB DRAM is not supported.
• Supports DDR3/DDR3L 1866/1600/1333 non-ECC, un-
buered memory
• Max. capacity of system memory: 16GB .............

But it's not clear to me the meaning of * 2GB DRAM is not supported.

Does it means 1gb+1gb or 2gb+2gb ?