Paraphrased from RA XXXVII Troia capta
Trōiānī equum ligneum Minervae, deae Trōiānīs benignae, sacrātum esse putābant, . . .
Are Minervae and Troianis both Dative of Reference and is benignae Dative of Purpose?
No. Minervae is a dative complement to sacratum esse, and deae stands in apposition to Minervae, benignae modifies deae, and Troianis is a dative complement to benignae.
On the “double dative” construction:
Gratias tibi ago!