Can Paypal Standard and Paypal Express be used at the same time?

Topic says it all;
Can Paypal Standard be enabled and Paypal Express at the same time?

Also, I notice when using Paypal Standard items get removed from stock before they are actually paid for (when customer is directed to Paypal)
Is there a way to change this so they only get removed when payment takes place?

Unfortunately not.
At least till version 3.0.
Any redirection method won't give you that functionality.

PayPal express originally won't give you functionality you are looking for, simply because that's as well redirection payment method.
We implemented placing an order only after paypal payment made. But i was need to:

1) Implement additional table to put all the neccessary information (such as checkout attributes, additional data such as Nominated Day delivery)
2) Copy PlaceOrder method with some modifications into the plugin.

Issues when item became is out of stock while customer was on the paypal could have a place, so that you have to process additionaly.

I am running 3.1, does this affect your answer?

I suppose not.

Sorry i missed answer for your question.
PayPal Standart and PayPal Express can be used together.

But as I said, that won't bring you expected functionality.
Simplest way to do it - not to amend stock in the PlaceOrder method (core change) and amend stock after customer redirected back to you (this part could be done in plugin).
More hard way - as i described above.

Is this code you've done before?

Do you have it available to review?

Unfortunately that coding done "On Fly" in big rush, with several core changes, so code is in huge mess and code refurbushing require. Another reason I can't upload it on public - this code will be a property for Brastop.com, and just company director can decide give it to public or not.

I understand.
Thanks!