My boy is showing how it's done:

• Communist sperms:

For the males, their testes never descend, they have no scrotum, when not in use, their penis is stored internally and their ejaculate contains bundles of up to 100 sperm that swim cooperatively until they reach the egg.

• Doesn't get tired:

By alternating the use of each side our tame echidna can ejaculate 10 times without significant pause, potentially allowing him to out-mate less efficient males.

Bonus:

• Platypus doesn't send dick pic:

Superficially, the platypus penis looks very different – not only does it have only two heads (or glans), but, the entire penis is covered with distinct keratinous spines. However, the internal structures appear very similar to those in the echidna. Currently, we don’t have any data on what an erect platypus penis looks like so we don’t know if they use both at the same time.

Source ( gold ) https://pursuit.unimelb.edu.au/articles/solving-the-mystery-of-the-four-headed-echidna-penis