والعبد بين شريكين لا فطرة على واحد منهما
Translation: For a slave jointly held by two partners, neither partner is liable for his fitrah under this ruling.
“Between two partners” identifies joint ownership. The manual assigns it a particular historical ruling; it does not require each partner to pay half of a fitrah.
The statement is limited to this particular legal case and should not be extrapolated to unrelated arrangements.