Processing question of Sentinel1 WV mode

I have came cross little difficulty in processing Sentinel1-SAR WV mode data by SNAP. So that’s why i ask for your help. The questions i have listed as:
(1) Each WV mode data has two bands, which corresponds to two incidence angle. And each band has about 30 small data sets, However, when i do the geometric operation, the 30 small data sets seems correspond to same geographic position. Don’t the WV mode acquires data in 20 km by 20 km vignettes, at 5 m by 5 m spatial resolution, every 100 km along the orbit? How should i do to split each vignette from the each single downloaded file?