Know for sure? No.
Here is what you did. At the beginning of the disk is a partition table. Let's assume that it is a modern GPT partition table; those things are a few dozen KB long. There is a second backup copy of the partition table at the end of the disk (that's part of the GPT specification). Using dd, you severely damaged the partition table, by overwriting the first 1KB of it: The dd command you used write two blocks, each 512 bytes long (that's the default block size in dd). At this point, you have a "broken" disk. By broken I mean that the two copies of the partition table, at the beginning and end, are different.
Then you created a UFS file system. How did you do that? Did you partition the disk first (for example using gpart
)? And what device did you create the file system on, /dev/da0 (which would be the whole disk, including the partition table), or /dev/da0p1 (which would be the first partition table)? If it is the former, then the UFS file system has now completely blown away the first partition table. If it is the latter, then I wonder what partition table was used to define /dev/da0p1, since the one at the beginning of the disk is already damaged.
Then you rebooted. I have no idea how FreeBSD reacts when the two copies of the partition table are different. But what's worse: There are some helpful BIOSes which verify that each copy of the partition table is uncorrupted (the one at the beginning was at this point at least damaged, perhaps completely blown away), and if they find one good one and one corrupted one, they "helpfully" (ha ha) overwrite the damaged one with the good one. If you have a UFS file system on /dev/da0, and the BIOS "helpfully fixed" the partition table, then you now have a UFS file system with the very first bit damaged by an old partition table having been dropped on top of it, like a piano falls out of a window in a cartoon. Even if your BIOS did make things worse, you still have something broken, and it's hard to guess how tools react to broken on-disk data.
Then you ran TestDisk. I have no idea what it does. The fact that it shows two contradictory things demonstrates that your disk is pretty confused right now.
Before we can really help, we'll need a lot more information, both about what exactly you did (ideally you have records of which commands you ran), and some output from programs such as gpart to show what the current state of affairs is.
Honestly, I fear that repairing this after the fact will be so difficult as to be practically impossible, but maybe the damage is only slight.