Amazon SQS has just gained FIFO Queues with Exactly-Once Processing & Deduplication:
Today we are making SQS even more powerful and flexible with support for FIFO (first-in, first-out) queues. We are rolling out this new type of queue in two regions now, and plan to make it available in many others in early 2017.
These queues are designed to guarantee that messages are processed exactly once, in the order that they are sent, and without duplicates. [...]
[emphasis mine]
As emphasized, these new FIFO SQS queues will render any special considerations to consume Amazon SQS messages in true FIFO unnecessary, but are not yet available in all SQS regions [initially only in US East (Ohio) and US West (Oregon)].