Might we consider giving our guest, Emily, actual NAMES OF SONGS which are preferable for 2 female voices to harmonize?

Having said that, some of my old favs which are easy to harmonize ("gospel" 3rds most of the way) & enjoyed by most audiences, are often overlooked 'cause they are from the old tried & true department (most are Traditional or in the public domain):

Bluegrass--MIDNIGHT ON THE STORMY DEEP--a Traditional song which has long been thought of as a powerful duet (with lyrics adjusted to all be in the female 1st person)

also, DON'T THIS ROAD LOOK ROUGH AND ROCKY or ANGEL BAND--gospel 3rds most all the way through, good to learn harmony.

Hymns---IN THE GARDEN, Sweet Hour of Prayer, or WHISPERING HOPE

Gospel-----When The Roll Is Called Up Yonder, His Name Is Wonderful, KEEP ON THE SUNNY SIDE, & zillions of others

Spirituals----In The Upper Room With Jesus (the really old one Mahalia sang!), THERE IS A BALM IN GILEAD, STANDING IN THE NEED OF PRAYER, SINNER WILL BE RUNNIN' ON THAT GREAT DAY, & tons more.

From the old-time hit parade----Catch A Falling Star (and put it in your pocket), VAYA CON DIOS, DON'T LET THE STARS GET IN YOUR EYES (I liked Homer & Jethro's lyrics [DON'T LET THE STARS GET IN YOUR EYEBALLS] better, & you can find their lyrics in old mudcat threads!), Standin' On The Corner (watchin' all the girls/boys go by) True Love (I give to you & you give to me, Love forever true==Sung in the old movie by Bing & Grace Kelly! before it was resurrected a few years ago), He Loves and She Loves, & lots of other Broadway songs.

From the great composer of great operas:
Rossini--Duetto Buffo di du Gatti (comic duet of the cats-aka: sopranos) preferably sung in the original Italian lyrics: "Miau." This one may be my all-time fav duet to perform!