If I do this

n = 35;
a = (x*2) + 3;
b = (a + Sqrt[(a)^2 - (n*4)])/4;
c = (x*2) - 9;
d = ((c) + Sqrt[(c)^2 + (n*4)])/4;
e = Column[N[Table[{b, d}, {x, n, 5, -1}]], Frame -> All]

That doesn't change any of your code except adding N so I can see decimal values for all your numbers... then Mathematica displays

{{36.258678463452, 30.784236382905984},
 {35.25178562318713, 29.79368638333038}, 
 {34.24448439935734, 28.803779577827882},
 {33.236737093797544, 27.814583179035203}, 
 {32.228501181274794, 26.826173982385463},
 {31.219728504404983, 25.838640112708426}, 
 {30.21036430037718, 24.85208316112856},
 {29.200346016618425, 23.86662081605263}, 
 {28.189601859450647, 22.88239012413184},
 {27.178049001995785, 21.89955156048888}, 
 {26.16559135308949, 20.918294146675933},
 {25.15211675481246, 19.938841936157417}, 
 {24.137493427968742, 18.961462299777516},
 {23.12156541554416, 17.986476600955584}, 
 {22.104146673046206, 17.01427407147905},
 {21.085013304297192, 16.04533001151853}, 
 {20.06389321319526, 15.080229881682913},
 {19.040452088031024, 14.119701486491838}, 
 {18.01427407147905, 13.164658342969666},
 {16.9848345460003, 12.216258578188782}, 
 {15.95146090037468, 11.275985396596976},
 {14.913274390947201, 10.345757321399848}, 
 {13.869101147436863, 9.428078794301996},
 {12.817330549755798, 8.5262432936357}, 
 {11.75567888638631, 7.644598957811737},
 {10.680770730829005, 6.788873605350878}, 
 {9.587337893224369, 5.966517186829627},
 {8.466517186829627, 5.18693177121688}, 
 {7.3016389039334255, 4.461308144666282},
 {6.054886114323222, 3.8016389039334255}, 
 {4.596291201783626, 3.218585521759479}}

That looks like your numbers are already in descending order in each column.

Is that what you wanted? Or do you need some other ordering?

If it would be easier for you to create two tables and then combine them then try

t1=Table[i^2,{i,1,3}];
t2=Table[2i+1,{i,1,3}];
Column[Transpose[{t1,t2}],Frame->All]

and you should see two nicely formatted columns of numbers.

If there is something else you need and you can explain so that I can understand then perhaps I can find a way to modify this.

That helped me understand

n = 35;
a = (x*2) + 3;
b = (a + Sqrt[(a)^2 - (n*4)])/4;
c = (x*2) - 9;
d = ((c) + Sqrt[(c)^2 + (n*4)])/4;
e = Column[Reverse[Sort[Flatten[Table[{b, d}, {x, n, 5, -1}]]]],Frame->All]

Perhaps https://reference.wolfram.com/language/ref/Union.html

If you can show the exact code you are using so that I can exactly reproduce your results, and you can describe exactly what the duplicate rows are, so I can identify them here, then I will see if I can find what mistake I made and we can try to get this fixed for you.

One last question, do you know how a second column to the first?

Crossposted here.