discharge for the effluent each succeeding lower screen receives mud effluent which has passed through the screen above etc in the present invention a shaker 35 includes two parallel juxtaposed screens 36 37 separated by removable trays 75 located in parallel with and juxtaposed with screens 36 37 openings or bypass 70 are formed in the sides of shaker 35 between screen 36 and trays 75 shaker 35 further includes a first feed inlet 38 and a second feed inlet 39 fig2 and 3 shaker 35 also includes a mud tank 60 below screen 37 fig4 and an inlet hopper or box 65 fig7 positioned on the upstream side of feed inlets 38 39 mud 12 is received from the drilling rig 15 through inlet hopper or box 65 at the two separate levels level 1 fig2 from feed inlet 38 which flows 40 onto screen 36 and level 2 fig3 from inlet 39 which flows 45 onto screen 37 waste cuttings are also discharged at two separate levels 50 55 from screens 36 37 respectively as shown in fig2 the effluent 47 from the upper screen 36 is discharged directly to a mud tank 60 as shown in fig4 thus bypassing the lower screen 37 and the effluent 46 from the lower screen 37 is discharged directly to mud tank 60 as shown in fig4 this greatly increases the volume which can be processed by one shale shaker 35 the results are two shale shakers in one location thus the name 34 two for one shale shaker 34 as shown in fig1 4 and 5 the mud flows from the drilling rig 15 via pipe 105 to the two.