Do two standard actions equal a full round action?

Question

If a character was somehow able to get two extra standard actions on their round in combat, could those actions be used as an extra full attack action or full round action?

Elaboration: In the first round, on its turn, a character can, instead of doing a full round action, do both a standard action and a move action. Also, a character can, instead of doing a standard action, do a move action. Say one character starts its turn with two extra standard actions (and possibly makes one into a move action).

Answer 1

No, a full round action does not equal two standard actions. It takes place instead of all actions on your turn (except free actions).

From Actions in Combat on the d20srd:

Full-Round Action

A full-round action consumes all your effort during a round. The only movement you can take during a full-round action is a 5-foot step before, during, or after the action. You can also perform free actions (see below).

Emphasis added.

In fact, if it equalled two standard actions, that would be a problem: you only have one standard action in a turn! Normally you're swapping your standard and move action, remember.

Can you exchange extra standard actions for a full one? I don't know if there's rules around that, and your GM may say yes. A full round action should be exactly that though: your full round. Then again, that wasn't written with someone who has three standard actions in their turn in mind.

Answer 2

No, but...

As doppelgreener points out, a full-round action takes up your whole round, but you can spend a standard action to start or complete selected full-round actions. Not all full-round actions are available, and the caveat is that you have to complete it on the following round (not in the same round).

Start/Complete Full-Round Action

The "start full-round action" standard action lets you start undertaking a full-round action, which you can complete in the following round by using another standard action. You can’t use this action to start or complete a full attack, charge, run, or withdraw.

The restriction on attacking, charging, running and withdrawing makes this of limited use, but if you could maintain the state of having three (or more) standard actions over multiple rounds, then you could use your last action to start a full round action, finish it with your first standard action of the next round, then use your "spare" standard actions on whatever else, giving you a full-round action per round, plus standard actions for other things.

Going beyond the RAW, this does somewhat imply that full-round actions are roughly equivalent to two standard actions.