Marcus and Markieff Morris have turned themselves into solid NBA players. The twins are the heartbeat of the Suns bench and are so close that it seems they share one heartbeat. At what financial sacrifice are the Morris twins willing to make to keep that together? What are the Suns willing to pay to avoid finding out what might suffer with only one — or none — of them? The Morrises are under contract for the last years of their rookie deals next season but they will be eligible in the fall for contract extensions, which surely will be one of the more peculiar negotiating situations in franchise history. The theory that they would play better if reunited has been undeniably proved. Markieff has become a Sixth Man Award candidate with 13.3 points and 5.8 rebounds per game, sixth- and fourth-best, respectively, among NBA reserves. His seven double-doubles lead all bench players. Marcus adds 10.1 points and 4.1 rebounds per game, usually complementing Markieff at forward or serving as the team’s two big men in a smaller lineup that helps prevent a drop-off when the starters leave. The preference for the twins is an easy call. They want to remain teammates and stay in Phoenix. The Suns will have to decide whether they want to invest more heavily in keeping them together long-term or risk losing both or signing just one. If one stays, how will he respond to losing his best friend again? Both were not giving near the quality of play on separate teams. They now provide each other constant support, from a shared home to coming and going everywhere at each other’s hip in US Airways Center. “We think about it a lot,” Markieff said. “We said in the beginning that if we ever get together, we’re going to stay together. We do our best to compete and show how good we are together.