How does SPIA amplification in Ovation RNA seq v2 kit produce dsDNA?

I am trying to use the Ovation RNA seq V2 kit from Nugen or Tecan to amplify low-input RNA (about 1ng). (

The Protocol and workflow of the SPIA amplification process show linear amplification of cDNA, which is single-stranded (As per the schematic provided by them). However, the kit claims it generates double-stranded cDNA, which is not shown in the figure or explained how it is done!!!

Can somebody please help me understand this?

How does the Ovation RNA seq v2 kit generate double-stranded cDNA instead of single-stranded cDNA??!!

Nugen/ tecan suggests using their library preparation kits (for Illumina) which can utilize only dsDNA templates but not single-stranded.
They seem to work well, but I don't understand how the dsDNA is generated in the amplification step (RNA Seq V2 kit).

Please help.