I have seen this a few times and never really gave it much thought. Why does it have an up and down arrows or how does it behave differently than a regular dropdown.
Use a pop-up button to present a flat list of mutually exclusive options or states. A pop-up button helps people make a choice that affects their content or the surrounding view. Use a pull-down button instead if you need to:
- Offer a list of actions
- Let people select multiple items
- Include a submenu
Evidently, that's not what's going on in your screenshot though.
Stepping back from any concrete design guidelines, I'd say that a dropdown indicates that the options will appear below, whereas this indicates that options may appear above and below, or, in the case that this field actually is a text input field, that clicking the up/down part will expand the field into a multi-line textbox.