Whats going on here?

Hi I just started using Rhino 6 from Rhino 5 and I keep seeing these odd lines that I have no idea what they are there for. Please see the attached picture.

I seems to be happening when I duplicate an object? I dont know though. Any help to understand this is appreciated!

I changed the topic category to Rhino for Mac (from your screenshot). We have seen some instances of this before, it has to do with your graphics card and the age of the machine IIRC, can you run SystemInfo in Rhino and copy/paste the results here?

Rhino 6 SR24 2020-3-19 (Public Build, 6.24.20079.23332, Git hash:master @ 064283610b834170e52117f2656605b5b25d65c0)
License type: Evaluation, build 2020-03-19
License details: Stand-Alone
Expires on: 2020-05-28

Apple Intel 64-bit macOS Version 10.13.6 (Build 17G8030) (Physical RAM: 8Gb)
Mac Model Identifier: iMac12,2
Machine name: admin’s iMac
Language: en-CA (MacOS default)

AMD Radeon HD 6970M OpenGL Engine (OpenGL ver:4.1 ATI-1.68.23)

OpenGL Settings
Safe mode: Off
Use accelerated hardware modes: On
Redraw scene when viewports are exposed: On

Anti-alias mode: 4x
Mip Map Filtering: Linear
Anisotropic Filtering Mode: Height

Vendor Name: ATI Technologies Inc.
Render version: 4.1
Shading Language: 4.10
Maximum Texture size: 16384 x 16384
Z-Buffer depth: n/a
Maximum Viewport size: 16384 x 16384
Total Video Memory: 1 GB
Graphics: AMD Radeon HD 6970M
Displays: iMac (109dpi 1x)

Graphics processors
AMD Radeon HD 6970M (1024 MB)
iMac (2560 x 1440)

USB devices
Microsoft: Microsoft® 2.4GHz Transceiver v8.0
Apple Computer, Inc.: IR Receiver
Apple: Internal Memory Card Reader
Apple Inc.: FaceTime HD Camera (Built-in)
Logitech: USB Receiver
Apple Inc.: Bluetooth USB Host Controller

Bluetooth devices

Third party kernel extensions

Third party plugins

Rhino plugins
/Applications/Rhinoceros 2.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/RhinoCycles.rhp “RhinoCycles” 6.24.20079.23332
/Applications/Rhinoceros 2.app/Contents/PlugIns/NamedSnapshots.rhp “Snapshots” 6.24.20079.1002
/Applications/Rhinoceros 2.app/Contents/PlugIns/RhinoBonusTools.rhp “Rhino Bonus Tools” 6.24.20079.1002
/Applications/Rhinoceros 2.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/GrasshopperPlugin.rhp “Grasshopper” 6.24.20079.23332
/Applications/Rhinoceros 2.app/Contents/PlugIns/MeshTools.rhp “MeshTools” 6.24.20079.1002
/Applications/Rhinoceros 2.app/Contents/PlugIns/PanelingTools.rhp “PanelingTools” 6.24.20079.1002
/Applications/Rhinoceros 2.app/Contents/PlugIns/import_STL.rhp “STL Import” 6.24.20079.1002
/Applications/Rhinoceros 2.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/Commands.rhp “Commands” 6.24.20079.23332
/Applications/Rhinoceros 2.app/Contents/Frameworks/RhMaterialEditor.framework “Renderer Development Kit” 6.24.20079.1002
/Applications/Rhinoceros 2.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/RDK_EtoUI.rhp “RDK_EtoUI” 6.24.20079.23332
/Applications/Rhinoceros 2.app/Contents/PlugIns/Displacement.rhp “Displacement” 6.24.20079.1002
/Users/admin/Library/Application Support/McNeel/Rhinoceros/MacPlugIns/ProjectObjects.rhp “ProjectObjects”
/Applications/Rhinoceros 2.app/Contents/PlugIns/SolidTools.rhp “SolidTools” 6.24.20079.1002
/Applications/Rhinoceros 2.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/RhinoDLR_Python.rhp “IronPython” 6.24.20079.23332
/Applications/Rhinoceros 2.app/Contents/PlugIns/RhinoRender.rhp “Rhino Render” 6.24.20079.1002

you may want to update your OS to at least 10.14.6 if not the full up to date version-