So I've experimented with Petri Laarne's answer from StackOverflow and finally come up with a workable code (most examples online are using C#, and doesn't explain the entire process). Trying to explain it here:
In Public Class Game1:
Private WithEvents graphics As GraphicsDeviceManager
Private WithEvents spriteBatch, spriteBatch2 As SpriteBatch
In Loadcontent:
Public render2 As RenderTarget2D
spriteBatch2 = New SpriteBatch(GraphicsDevice)
spriteBatch = New SpriteBatch(GraphicsDevice)
render2 = New RenderTarget2D(GraphicsDevice, 1024, 768)
In Draw:
spriteBatch2.GraphicsDevice.SetRenderTarget(render2)
GraphicsDevice.Clear(Color.Black)
srcRect = New Rectangle(440, 0, 440, 440) : destRect = New Rectangle(100, 335, 440, 440)
spriteBatch2.Begin(SpriteSortMode.BackToFront, BlendState.AlphaBlend) : spriteBatch2.Draw(introNEWMirrorDecos, destRect, srcRect, Color.White) : spriteBatch2.End()
destRect = New Rectangle(300, 335, 440, 440)
spriteBatch2.Begin(SpriteSortMode.BackToFront, BlendState.AlphaBlend) : spriteBatch2.Draw(introNEWMirrorDecos, destRect, srcRect, Color.White) : spriteBatch2.End()
spriteBatch2.GraphicsDevice.SetRenderTarget(Nothing)
GraphicsDevice.Clear(Color.Black)
destRect = New Rectangle(512, 384, 1024, 768) : srcRect = New Rectangle(0, 0, 1024, 768)
spriteBatch.Begin(SpriteSortMode.BackToFront, BlendState.AlphaBlend) : spriteBatch.Draw(render2, destRect, srcRect, Color.White, PI / 12, New Vector2(512, 384), SpriteEffects.None, 0) : spriteBatch.End()
This is an example code from the actual game that worked like it was intended: drawing 2 things on the alternate rendering image and then drawing them as one single image (in this case being able to rotate it by pi/12).
Any comments on how to do this differently or more efficient is appreciated