Extend Spell question

[Markov Spiked Chain]

How does Extend Spell work with:

Command
Duration 1 round
... On its turn,...

Murderous Command
Duration 1 round
...The target attacks its nearest ally on its next turn with a melee weapon or natural weapon...

Deja Vu
Duration 2 rounds
...Whatever full-round, standard, or move actions the creature takes on its first turn after you cast this spell, it must repeat on the turn after that....

I think most people assume they would add another round of effect. But I'm not totally sure how the "next turn/turn after that" wording interacts with extending the duration.

[Fuzzy-Wuzzy]

Command: for the next two rounds the creature must try to obey the order you gave at casting. Minor twist: if they are unable to obey it on their first try, the spell ends, so they don't get their second try.

Murderous Command: target acts murderously for its next two turns. This may result in first moving closer to an ally and then closing the distance and attacking.

Deja Vu: lasts four rounds total since the duration is what gets doubled, so whatever the target does on its turn following the casting it must do thrice more.

Don't put too much weight on the singular nature of the phrase "next turn," basically. Look at it this way: if this doesn't actually mean "for the duration of this normally one-round spell," what would they have had to say to mean that? Answer: something that would confuse people far more often than it helped. (Hope that argument makes sense.)

[Plausible Pseudonym]

I'm not sure an extended Deja Vu shouldn't make you repeat on rounds 2 and 4 your actions on rounds 1 and 3.

[Markov Spiked Chain]

Sounds like the concensus is mostly that it works. Extended Deja Vu, or Extended Command+Extended Deja Vu seems particularly good.