Where does “dual monastery” come from?

dual monastery (English) comes from English monastery, from Old French monastere, from Latin monastērium, from Ancient Greek μοναστήριον, from Ancient Greek μόνος, from Ancient Greek σπέρμα, from Proto-Hellenic *spérmə.

Ancestry of “dual monastery”, step by step

dual monastery traces back through two separate lines of ancestry.

via English monastery

StepLanguageWordMeaning
1EnglishmonasteryBuilding for housing monks or others who have...
2Old Frenchmonastere
3Latinmonastēriummonastery
4Ancient Greekμοναστήριονsolitary dwelling, hermit's cell; monastery
5Ancient Greekμόνοςalone, forsaken, solitary; only; unique
6Ancient Greekσπέρμαseed; semen, sperm; seed-time, sowing
7Proto-Hellenic*spérmə

via English dual

StepLanguageWordMeaning
1EnglishdualCharacterized by having two (usually equivalent) components
2Latinduālisdual
3Latinduōtwo; 2
4Proto-Italicduōtwo
5Proto-Indo-Europeandwóh₁two
Every word from Proto-Hellenic *spérmə