Remove units vlm cuve once the $vlm one comes up

piker/ui/_fsp.py

@@ -246,7 +246,6 @@ async def run_fsp_ui(
                 overlay=True,
                 color='default_light',
                 array_key=name,
-                separate_axes=conf.get('separate_axes', False),
                 **conf.get('chart_kwargs', {})
             )
             # specially store ref to shm for lookup in display loop
@@ -769,6 +768,7 @@ async def open_vlm_displays(
             # displayed and the curves are effectively the same minus
             # liquidity events (well at least on low OHLC periods - 1s).
             vlm_curve.hide()
+            chart.removeItem(vlm_curve)
 
             # use slightly less light (then bracket) gray
             # for volume from "main exchange" and a more "bluey"