You may get to see it twice but even the duplicate is queuing.
It's no big deal really if it posts twice. Xant had a double thread about her daughter's graduation, and had multiple replies on both threads.
My Noah's Ark thread double posted too with multiple posts on both. But they were all quite short threads and there was no need to combine them.
I have only every had one double thread combined since I have been here, it was years ago when I didn't know how internet forums worked, and I couldn't see my thread because I was looking in the wrong place.