You are correct but double the bottles times are a massive difference !
depends on the developer

i have processed 1/2 box speed exposed film in xtol for 2x the listed times on the olde kodak chart
and the film was thin and flat.
i know nothing about RO9 or rodinal
if it was sprint, dektol, ansco130, caffenol,
dk50. gaf universal, xtol, i might have been able to add something useful
but i'm on empty when it comes to rodinal ...
if you have time and effort and film to spare, i'd
do a development test,
photograph something full tone, outside, whatever
bracket your exposures by 1 stop ( so do 1 stop as your meter reads ( f5.6 for example )
then1 over and 1 under ( so f8 and f 4 )
and develop as it says on the bottle.
then do the same test and increase your development by 30 or 50% and see what happens
and what you like. people do all sorts of dilutions with rodinal from what i understand,
maybe your dilution was off, and your development time didn't reflect its concentration/