Dwight Howard may have filed for divorce Monday ... but TMZ has learned his estranged wife, Amber Howard, headed to court the same day to do the exact same thing.

Sources with direct knowledge tell TMZ ... Amber was also filing with her attorney ... but Dwight beat her to the punch, and his paperwork was processed first.

Despite the dueling divorce moves, we're told the estranged couple is still living together under the same roof at their marital home in Georgia for now.

Dwight was in California this weekend with his son, David, while Amber remained in Atlanta.

This isn't their first attempt at ending the marriage. Amber filed for divorce last year, but the pair ultimately reconciled and called it off. Our sources say this time it's different ... the split is definitive.

TMZ broke the story ... Dwight filed Monday, calling the marriage "irretrievably broken," and he asked for exclusive use of his Georgia mansion.

We first reported ... Gwinnett County Police were dispatched to the home three times in the past two weeks -- including for a suicide threat, a domestic incident and a theft report.

The filing came just days after Amber posted a series of shocking allegations about Dwight on Instagram.