TOEFL® reading comprehension question

[Galina Blanca]

Some acacias actually produce edible crops.****** Other Acacia varieties are valued for the sticky resin,called gum.********

THE SENTENCE THAT HAS TO BE INSERTED

Some acacias are popular in landscaping because of their graceful shapes,foliage and blossoms

The two possible options are marked with stars..

According to the answer key it's the first option ( i.e after the very first sentence)

So the sentence wud now read

Some acacias actually produce edible crops.Some acacias are popular in landscaping because of their graceful shapes,foliage and blossoms.Other Acacia varieties are valued for the sticky resin,called gum.

The explanation given: The connection between the sentences occurs in the first words - some and other,which determines consecutive order.

My doubt:Other does follow some ( 3rd sentence and 2nd sentence)

But some follows some too ( 1st sentence and second sentence)
Is this order allowed?

I hope i 've expressed my doubt clearly. If the question is unclear please post.

Can ne one explain?

Galina