In some stories they have no problem breeding with same stalk spawns or same parents different batch. Some stories have single type herds. It might just be the preference for another type is stronger like Chen-Ran.
I think I've read a story about Reimu trying to mate with another Reimu, hoping for a little one to come but they never come, because it is impossible for same type to have a little one.
her super cute little sis foreverMarisa will protectThat's why Marisa will let little sis take it easy until mommy and daddy come back