one USB scanner input to webpage and Excel simultaneously - is it possible?

Sequentially yes, simultaneously no. The Scanner software/driver pulls from one source while it is scanning (any scanner I have seen)

Your question is worded oddly.

You asked, "one USB scanner input to webpage and Excel simultaneously - is it possible?"

Scanners produce an image (normally .jpg format) or a PDF document which includes the scanned JPG along with a text component (searchable).

What you do with this PDF is up to you.

You can convert it to a webpage or convert it to pure text suitable for importing into Excel.

Note: Your data must be Excel friendly (tabular). There's no tool which can somehow format ad-hoc, non-tabular data, to tabular data, because infinite variation of this type of transform exists.

I've used a cheap ScanSnap machine for years. Full duplex scanning at roughly 1 page/second for $100 USD.

This little machine has saved me many times, when I had to convert some random scrap of paper into machine readable data.