This indicates that you have the domain configured to be hosted at DreamHost, that is to say the domain has been added to the hosting system via 'Add New Domain /Sub-Domain'.
Normally, if you want the domain to resolve to your IP address, you would first remove it from the DreamHost hosting system by going to Domains -> Manage Domains in the panel and clicking the small [X] link under the Web Hosting column. Once the changes have made their way through the system, the 'Non-Editable' DNS records should be removed, allowing you to add the 'blank' A-Record.
Having said that, I just did a small test on one of my test domains and added a 'blank' A-Record pointing to my home IP address. Surprisingly, this A-Record was added without error, even though the domain was configured to be fully hosted here at DreamHost, so I (like you) ended up with 2 'blank' A-Records, the one I added and the non-editable one pointing to the DreamHost server.
After flushing my local DNS with ipconfig /flushdns, I found that the domain was resolving to my home IP address.
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