Method to detect genome doubling
In a tissue or cell line that used to be diploid and has undergone genome wide doubling, you expect more variants having observed allele frequencies that would also occur in tetraploid organism. That is, observed VAF distribution will have (possibly small) peaks at 0.25 and 0.75, in addition to the diploid peaks at 0, 0.5 and 1. Compare the distributions in the tissue or cell line of interest to those of the control, that is, known diploid. Also if it is a doubled male genome, the sex chromosomes will show a new peak at AF 0.5, that is, heterozygous X or Y variants. This is just an idea, I have never tried to look for such events.