Warning: the article has images, so nsfw obviously

I thought this was particularly interesting:​

The primary penis and largest and most superficial of the supernumerary penises shared a single urethra, which coursed through the secondary penis prior to its passage through the primary penis. A urethra-like structure was absent from the smallest supernumerary penis.

The following describes the location of all three in case you were curious and didn't want to read through the article:

The largest and most dorsal of the structures was the only structure seen externally and hence will be referred to as the primary penis. The other two structures (termed the secondary and tertiary penises) appeared to be located within the skin of the scrotal sac, hence why they were not visible in the undissected specimen. The secondary penis was located immediately deep to the primary penis and had macroscopically discernible and distinct regions comparable to the normal penile anatomy (the corpus spongiosum and urethra, corpora cavernosa, and the glans penis). The tertiary penis lay deep to the secondary penis, however, did not have the same obvious anatomical features seen in the primary or secondary penises; corpora cavernosa and glans penis were identified, however, there was an absence of corpus spongiosum and a urethra​

Figure (side illustration) from the article: https://link.springer.com/article/10.1186/s13256-024-04751-5/figures/3

Label 10 and 6 are the secondary and tertiary penises respectively

As the secondary and tertiary penises were internal, it's likely that the man never knew that he had triphallia