Message order with multiple publishers to same latched topic

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According to the wiki :

latch [optional]

Enables "latching" on a connection. When a connection is latched, the last message published is saved and automatically sent to any future subscribers that connect. This is useful for slow-changing to static data like a map. Note that if there are multiple publishers on the same topic, instantiated in the same node, then only the last published message from that node will be sent, as opposed to the last published message from each publisher on that single topic.

So with your scenario your assumption is correct. For the order, I tried your scenario and there wasn't any specific ordrer when subscribing to the topic so no the order isn't guaranteed.