Congratulations on your little twin boys!
There's the usual names for grace, hope, love, gift, blessings, promise, mercy and peace (Chisomo, Chiyembekezo, Chikondi, Mphatso, Madalitso, Lonjezo, Chifundo, Mtendere) which could fit in the Christian sense.
I'm also partial to 'praise' or 'thankful' names like Mayamiko, Yamikani, Tiyamike, and Thokozani, which would work to thank God for much-wanted twins. Together they can sound very similiar though (e.g. Tiyamike and Mayamiko are a little to close in sound for me).
Or Alinafe? God with us.
Mphatso and Madalitso (gift and blessings)
Mayamiko and Yamikani (both fitting with a praise [God] meaning; Yamikani meaning be grateful)
Tiyamike and Chisomo (let us praise [God] and grace)
Thokozani and Yamikani (thank [God] and be grateful/praise)
Just some ideas.